Not Completely Useless

A video game offers you a variety of things to use against your enemies, you've been (or needed to be) making use of several and have been making progress just fine.

Then you meet a brick wall.

Whatever you use seems to get you slaughtered in the end, and the only viable way you can think of is either a long battle of attrition or a near-impossible precision strike. As a last resort before you throw the controller out the window, you try something (whether it be an item, spell, weapon, move or another thing) that you pretty much forgot about as it seemed utterly useless. Then you proceed to blast through the "difficult" moment without breaking a sweat, as this "useless" thing has just the right properties to get you through this situation... Then it remains utterly useless for 99.9% of the rest of the game.

This isn't something that you are "supposed", or necessarily need to use for that encounter, something Too Awesome to Use you were saving up, something that is genuinely useful in different situations or something that becomes awesome when upgraded; this is something you dismissed straight away (probably rightfully), whether because it sucked, or because of better alternatives, that just so happens to work perfectly (or, at the least, far better) for this specific situation, perhaps for some odd quality it has (that is sometimes also what makes it useless everywhere else), or some effect it has on an enemy. It almost goes without saying that this is a typical Guide Dang It moment.

Note that not all examples are as extreme as the one given at the start; this is any time where something is useless for most of a game but has an advantage over your main tools for some section or other, even if it is not a particularly large one.

Compare Chekhov's Gun and This Looks Like a Job For Aquaman. This is different from the Lethal Joke Item, which is actually useful for a broad range of enemies; it just appears useless at first, or requires something before becoming useful.

Expect gameplay spoilers in the examples.


 * The Undead Slayer in Adventure Quest Worlds is amazing in Doomwood due to it's unique quality of quickly becoming well over 9000 by a Spirit Power system that only works when fighting undead. Its normal power when out of it's element is pretty Dismal
 * The Viy fight in La-Mulana. Going by how the rest of the game is set-up you are led to believe that Spears are your only option for this battle. However, as spears shoot directly downwards you must get right above the boss's eye to damage it, which also happens to be where all its most dangerous attacks comes from, making it one of the harder fights in the game. There is another weapon that turns out to be a savior; Throwing Knives seem pretty useless when you get them, so you tend to forget about them, as the shurikens do more damage and are faster horizontally and spears have better vertical damage and speed. However, the Knives property of "sliding" along the ground until they hit a wall allows you to just stand back (dodging some weak projectiles) and bombard Viy while coming under very minimal danger yourself, instantly turning it into a very easy fight. As a bonus, the Throwing Knives will damage the regenerating tentacles as well, making them much less of a hassle.
 * The Throwing Knives did have one other big use—Hell Temple. While the area may be filled with false floors, a thrown knife traces the actual path of the floor—Passing right through the "gaps" to show the real path.
 * Throwing Knives also make a small number of puzzles much easier than they would be with other, more obviously applicable weapons.
 * The throwing knives are actually significantly stronger than shuriken, and can hit sufficiently large enemies twice (they go through most enemies). it's just that shuriken have a (usually) far superior movement pattern. And you can throw more shuriken at once than you can knives.
 * The last boss of Mystic Defender: it could be trivially defeated by using the weapon that bounces balls off walls and crouching in the lower right hand corner of the screen. The balls would bounce and hit the boss in just the right spot. The weapon was otherwise useless for most of the game.
 * In Wild ARMs 3, a skill by Luceid called "Dark Luceid" pretty much deals very low damage, even when Luceid is using it against you when you need to obtain him. Afterwards, you can fight an upgraded Bonus Boss called Power Trask (basically, an upgraded "regular" Trask whom you defeated earlier). Now unlike regular Trask which can be defeated easily after knowing a trick, Power Trask suffers none such weakness. It is also highly defensive towards elemental magic (which your party has been relying on for a good chunk of the game). The non-elemental magic available doesn't hit hard enough and Power Trask is, quite simply, a pure Stone Wall that laughs at your physical attacks. Cue Dark Luceid saving the day due to its mostly heretofore unknown "deal damage according to how many elemental resistances the target has" property. This same property is what usually makes it deal pitiful damage: not many enemies have full elemental resistance thus making this skill useless for 90% of the game. Makes you think that The Dev Team Thinks of Everything doesn't it?
 * Completing a sidequest involving directing an easily-lost scholar home in Star Ocean the Second Story earns you a stick called the Funny Slayer that instantly slays any enemies with "Funny" in their name when you hit them. Of course, the only enemies that fit that description(Funny Thieves) are The Goomba and pretty much go down in one hit even if you were Level 1 and unarmed. That is, until you hit the middle floors of the Cave Of Trials, which contain Metal Funnys and Funny Thieflvl 99 s (one of which is a floor boss.)
 * Vulcan Raven in Metal Gear Solid: it is implied you must use your missile weapons for this battle, which he can easily shoot down if you don't use them carefully. Alternatively, you can lay claymore mines around the arena and wait for him to step on them; this is one of the only good uses of claymore mines in the game.
 * In a similar manner, the relatively useless chaff grenades can be used to make the fight against the cyborg ninja much easier. They're also essential to taking out the M1 tank and can make the battle against Metal Gear Rex easier as well.
 * Space Megaforce; there are a few times that weapons that seem to be outclassed become life savers. In level eight, if you shoot the walls, pieces break off that can kill you. Most weapons, when upgraded, have bullet patterns that will hit the walls constantly. Your saving grace is the Sprite weapon, which is usually outclassed by the others. Also, when playing on Normal, Tricky, and Wild difficulties, weapons that don't do much damage per hit but can fill much of the screen with bullets tend to be good choices, but when you play on Hard or Hyper, the enemies become able to take much more damage before dying, which forces you to fight with weapons that do more damage to individual targets. Oddly enough, the weapon named "Multi-Direction Shot" turns out to be the best at this, making it excellent on Hard and Hyper but a poor choice for the other difficulty settings. (The game's difficulties, in order from easiest to hardest, are Normal, Hard, Hyper, Tricky, and Wild.)
 * Captain Cadaver in Maximo: he is immune to all your attacks except for swinging your sword while crouching so you can hit his peg leg. This is (almost) the only part of the game where crouching is useful.
 * The other time occurs against bomb-throwing skeletons: Attacking them normally causes their backpack of bombs to explode, whereas crouching and slashing at their legs causes them to collapse in a heap with a bomb still in hand (and ticking).
 * Final Fantasy V; Segments with large amounts of damage floors are pretty much the only areas where Geomancers are useful.
 * The same game has numerous other almost-useless classes with useful abilities; mastering those classes will confer those abilities on the Freelancer and Mime classes. For this reason, many players will level-grind with those classes and then never use them again.
 * Geomancers themselves are not very useful, but their special skill "Gaia" is incredibly useful for the first half of the game, thanks to it giving you a wide variety of potent attacks, all of which requires 0 MP.
 * Richter in Castlevania: Portrait of Ruin; His weakness is darkness element. Johnathan's Cream Pie subweapon is Dark element, and actually deals massive damage when mastered, although it's a bit awkward to handle. A lot of players ended up beating Richter with pie to the face, just because it's one of a few most efficient ways to handle the bastard.
 * In Aria of Sorrow, there is one enemy, the Iron Golem. 9999 life and only takes 1 damage from any attack. It's also the same game that has a soul that (allegedly) swaps the target's HP and MP values. Take a guess how much mana the Iron Golem has...
 * Killer Mantle also instantly kills Red Minotaurs. Dawn of Sorrow has a similar use for the Imp soul, which temporarily effectively switches all enemies' HP and MP. Iron Golem, once again, has thousands of HP and about 15 MP. The multi-hit bonus weapon Terror Bear makes it even easier.
 * The Scutum glyph in Order of Ecclesia is, for the most part, functionally useless - it's just a shield that appears above your head, and doesn't appear in front of you like it is expected to. Its later forms, Vol Scutum and Melio Scutum, both appear in front of you. However, Scutum earns its respect in the Dracula fight, where it completely negates every shot that rains down during his Destruction Ray attack, which is quite tough to dodge otherwise. In combination with Melio Scutum, it can also effectively block his extremely deadly stream of bats attack.
 * It gets even better: Goliath's punching attack to the ceiling causes rubble to drop. Scutum negates this as well. It's easy to avoid on Normal mode, but Hard mode makes the ceiling drop much more debris so it's much more useful. Scutum has a third, awesome use - on Barlowe's homing fireball attack. Just stand below him and use it. All the fireballs just hit it and do nothing. On Hard mode, this is almost required as they are nigh impossible to dodge.
 * Going all the way back to Castlevania II: Simon's Quest, the Golden Dagger (obtained in the fifth mansion, right before the room with Dracula's Ring) is a powerful, straight-line projectile. However, it costs hearts to use, and by the time you get it, you have a ton of faster ways to deal with enemies. However, if you use it on Dracula, he'll be pinned to his starting location in the center of the room as long as you keep throwing them at him, becoming easy pickings (presuming you don't just use laurels to give yourself invincibility).
 * In Castlevania II, Sypha's flame spell is strong, but it has about the same range as \Trevor's whip, so generaly it's better just to use the whip. however, Trevor can only damage Dracula's first form by whipping his head, while Sypha's flame can damage Dracula's first form anywhere.
 * Circle of the Moon features the Zombie Dragons: A Dual Boss that easily earns That One Boss status. One of the reasons for this is that they are both above you (and a lack of platforms and good attacks doesn't help). But you may recall the Ax, the subweapon that you stopped using because it goes in an overhead arc...
 * More in line as a subversion. Those axes still do not do enough damage to outclass the cross. To be even more frank, if you do not catch the cross, the rebound can score a free hit or two on the OTHER dragon. It's useful, but you still won't touch it. The knife on the other hand...
 * Mondo Mole in EarthBound - one of the few bosses that is susceptible to PSI Paralysis Alpha.
 * Master Belch can either be fought the easy way, with the Jar of Fly Honey, or the really hard way, which involves the otherwise-meaningless HP Sucker and exploiting his weaknesses to Hypnosis and Paralysis. (You have to drain his HP from him because he won't take damage from attacks without the Fly Honey.)
 * Shroooom! can be a rather tough boss...unless you use the otherwise nigh-useless PSI Flash Beta against him, which will either paralyze or kill him in one shot.
 * In the Mega Man series:
 * The last boss in Mega Man 3 goes down to one hit of Top Spin. Top Spin is otherwise considered one of the most useless weapons in the series, although with practice, it can be mastered.
 * Also, starting with Bubble Lead against the final boss of 2, the most unwieldy weapon is often the final boss's weakness, except in.
 * Mega Man 2's Bubble Lead is also one of the only weapons that can take out those darned floor crawling spring enemies, and can show you where there are disguised holes in the floor by falling though them.
 * In 7, you remember those Wild Coils? You will when you fight Wily!
 * In 8, one of the boss's weaknesses...well, the only thing you could probably use against it save for Astro Crash, is the mostly neglected Mega Ball.
 * The Mega Ball also permits you to perform multiple midair jumps if your timing is good. Not Completely Useless!
 * Actually averted more often than not with Sigma in the Mega Man X series. In X1, he was weak to Rolling Shield, the charged version of which is extremely useful; in X2, he was weak to the Strike Chain, which had limited weapon use but was a good tool in several situations; and in X3, he was weak to the X-Buster only.
 * Mega Man Battle Network brings a really odd one to the table. The Minibomb chip in the standard series games is useless - you can't hit with it worth a damn against most things and it barely does more damage than any of the many chips you do have that are way more accurate. For the series' platformer Gaiden Game, however, it became a Game Breaker that went largely unnoticed because of its terrible history in the other games. For this one game, it was extremely easy and efficient to use, cheap to maximize your stock of, available right from the moment you hit New Game, and because the explosion damaged enemies multiple times, was capable of one-shotting half the enemies in the game; and everything else could be taken down with a second one if it wasn't a boss or had an aura (as enemies in two endgame stages did).
 * World of Warcraft: In the early days of raiding, hunters received a new ability, Tranquilizing Shot. It's only use was to remove frenzy effects found on some of the bosses (which would make them much stronger). Ironically, due to issues hunters had, this one trick made hunters much more likely to even get into raids. The second expansion finally gives it a broader range of uses, even against other players. A similar case was the Mage spell Detect Magic (shows active buffs on the target) which was very helpful on some bosses that required the raid to dispel certain effects otherwise hard to see, but in this case, the spell was eventually removed (and buffs made always visible).
 * Another classic case of this is the Warlock spell Detect Invisibility. Until Mages got a corresponding skill this was completely useless (Rogues use Stealth, which is a different mechanic) with a few select locations that have invisible enemies. Even there it's not necessary to use the spell, but it avoids nasty surprises (especially in Naxxramas where the first player the monster spots usually gets killed in one hit.
 * Yet another rarely used skill is "Mind Soothe/Soothe Beast". What does it do? It reduces the radius of the target in which it attacks players. If the spell fails, it attacks the target. Nowadays almost forgotten, there were a few places where players could avoid some fights with it, and in a specific case it's often used as a means to let the priest get close enough to the target safely to mind control it. Speaking of which...
 * Mind Control, while perfectly viable in PvP used to have the fatal drawback of making the target very pissed at the caster (a squishy priest) when it breaks off. This was later changed along with the possibility to use the spell to force some enemies to cast very useful buffs on the priests party.
 * Yet another overlooked spell is "Dampen/Amplify Magic", a buff that either decreases or increases magic effects (both damaging and healing). Since healing is almost always required and magic damage all too common, it's pretty much restricted to a choice few bosses that predominantly hurt with physical damage as a means to make healing a bit easier. The dampening variant is reasonably useful for mages playing on their own though, since they have no healing spells.
 * Undead enemies in Final Fantasy Tactics Advance rise again a few turns after being killed, unless a skill like Burial is used on their remains. Needless to say, those skills are completely useless anywhere else in the game. In the sequel the same goes for the Bard skill Requiem, which damages undead.
 * The Viking class is an awkward combo of stealing skills and spells. The spells are, for the most part, not worth using, with the exception of Tsunami, which can only be used if the caster is standing in water.
 * Oddly enough, the zombie status itself is rather useful - if you get zombified, you will automatically come back to life in several turns, without having to use Raise/Arise or a phoenix down!
 * Possibly the king of this trope from the Tactics series, however, is the Squire from the original game. Tackle, Counter Tackle, and Rock Throw are all usually rather pathetic abilities as far as damage goes. What bumps them into Not Completely Useless territory, however, is their ability to knock the target back a square. This can enable you to open an exit path for that party member, force an attacker to come back rather than performing a hit-and-run, hit an opponent and shove them out of range for their own counter-attack...and send them plummeting off a sheer cliff to the tune of colossal, and likely fatal fall damage.
 * One of the first weapons you get in Metal Mutant is some kind of lightning attack. It looks cool and is pretty strong in raw power, but it has an overly long charge time, its range is limited, andanyhit will take you out of it. However, there is one certain enemy near endgame that is totally impervious to everything you have except for this weapon.
 * Most Einhander strategy guides recommend the Endymion Mk. II and dismissed the Guns Akimbo Astraea fighter as Awesome but Impractical. But, equipped with the right pair of gunpods (that seem fairly useless on the Endymion) the Astraea chews through mooks and bosses alike with ease.
 * "Magic Bullet" cards are fairly common in Collectible Card Games. In response to cards and game mechanics that could potentially unbalance the game, designers often include cards specifically to counter these effects. If done poorly, such cards are useless except if your opponent employs the tactic it's meant to counter; in this case it rarely works, because it generally just isn't worth putting a card in your deck that is only useful in one specific circumstance.
 * The Yu-Gi-Oh Card Game had a few blatant examples of this, such as Gryphon Wing, White Hole, and Anti-Raigeki, whose only uses were to negate specific overpowered cards. Then they discovered banning, and these counter cards quickly became dead weight. A less blatant example is Kuriboh, a mostly-underpowered card that for a while was the only effective way of stopping several one-turn-KO combos.
 * The card game Doomtown was especially bad at this. In one of the later expansions, the cards in question really were Magic Bullets--"Bullet" type cards were designed to insta-kill various character types.
 * Magic: The Gathering had the card One With Nothing, whose entire effect was "discard your hand." It was completely useless until a competitive deck came out that relied on giving the opponent a stream of cards and using spells that dealt damage based on the number of cards in an opponent's hand compared to yours.
 * The Pokémon Trading Card Game uses "Magic Bullet" cards in place of banning. One recent example is Machamp, who could instantly KO any non-evolved Pokémon at a time when non-evolved Pokémon was the norm in tournament play. Most cases are subtler than this, however.
 * Diablo 2 features a Paladin ability called "Holy Bolt". Virtually useless unless you're focusing on healing teammates or damaging Undead. Of course, only a 1/4 of all the monsters in the game are Undead so you're helpless against everything else, but Holy Bolt does smash the daylights out of Undead.
 * If you spec out a Paladin to maximize Holy Bolt's healing properties, you won't be able to hit any monsters past Act 3 Normal. On the other hand, with the right gear (Faster Cast Rate rings for the win) you can heal 500+ HP a second. Not bad for a game that allegedly doesn't have a healing class.
 * Though the Sorceress's Blaze (which makes fire appear where you walk) is mostly useless, it makes an effective kiting tactic against Duriel. More than most classes, the Sorceress desperately needs to stay out of his Instant Death Radius; with Blaze, you can get him to chase you around in a circle in your trail of fire until he eventually dies.
 * In Final Fantasy X you eventually fight Seymour on Mount Gagazet, where he is one of less than a handful of enemies to use the Zombie attack. You can fight this battle the long and hard way with Aeons and Overdrives, or you can just keep a few vials of otherwise useless de-zombify medicine handy.
 * Yuna's Nul-spells, a low-cost spell that hits the entire party and will protect them from one attack that matches the nulled element (NulBlaze will protect you from fire, NulTide will protect you from water, et cetera), are considered useless by some players. However, they can be very handy indeed when you know exactly what kind of elements are coming. Flans and Elements, in particular, will attack with specific elements, and if you cast the appropriate Nul- spell in time you won't be hurt at all. They're also very helpful the first time you fight Seymour, since he repeatedly casts each elemental spell in a specific order. If you know what's coming next (and the Sensor ability will explain the sequence to you), you can make what would be That One Boss much more bearable.
 * Petrifying enemies doesn't usually count for much in many Final Fantasy games, but in Final Fantasy X it's another matter entirely:
 * Having Rikku use Petrify Grenades on underwater fiends will instantly kill them, as they sink to the bottom and shatter.
 * In the desert on the way to the Al Bhed Home, you'll run into these weird plant fiends that will automatically cast Confusion on you every time you hit them...unless you use Kimahri's Stone Breath on them. Who'd have guessed that it would be so hard to confuse someone when you're petrified and about to shatter?
 * Digital Devil Saga: Null Sleep/Avoid Sleeper (avoid any attack so long as you're affected with Sleep status) is completely useless against nearly every boss in the game. Except one, where it is, in point of fact, absolutely required to succeed. Oh, and that one specific fight? That would be, most definitively on the short-list for hardest boss ever in the history of gaming.
 * Cielo has mediocre stats and a weakness to any skill that inflicts status ailments. Virtually every enemy has an attack that inflicts status ailments, so Cielo is often times a bad choice, even against electric enemies who he is supposed to be most useful against. The one time he is legitimately useful is in the same fight where the aforementioned Null Sleep is required. The reason is because his weakness to status ailments means he is almost guaranteed to be hit with the sleep status ailment.
 * In Persona 4 there are items that deal a fixed amount of damage, low even for the early parts of the first dungeon (and you don't find them till you get near the end of said dungeon!) make short work of Metal Slimes. Also good for exploiting elemental weaknesses without burning SP. Later on, however, you get the Magatama items, which deal 150 damage to all enemies; you'll likely find them useful on the bosses for the striptease and Void Quest dungeons.
 * Team Fortress 2 does this with several weapon choices. For instance, the Flare Gun is a replacement for the Shotgun as a Pyro which fires single-shot flares that do minor damage and ignite targets over long distances. However, at those distances, flares are hard to aim reliably and enemies can see them coming from a mile away and dodge them easily, while at closer rangers you may as well simply use your Flamethrower since the single-shot nature of the weapon renders it useless compared to the Shotgun when you need to pump repeated shots into your enemy. As such, the Flare Gun is normally relegated to a minor support role in distracting enemies from a distance, softening down crowds of enemies before your teammates engage them, or heckling Snipers trying to take potshots at your teammates. However, the Flare Gun's saving grace comes in its ability to land a guaranteed Critical Hit on enemies that are already on fire, so, if you need to provide heavy support fire for a friendly Pyro who's already torching enemies in the distance, or take down that revved-up Heavy in three shots, or simply hold down a long, narrow chokepoint like the 2Fort sewers alongside another Pyro, the Flare Gun is a man's best friend.
 * Ancient Domains of Mystery hangs a lampshade on this with the "potion of uselessness." When drunk, it's...useless. But if thrown in the Slippy-Slidey Ice World, it propels you along like any other thrown object...
 * Oh, it gets better. It's not merely useless if you drink it. It's useless if you throw it at a monster. It's useless if you dip an item in it. It's never an alchemical ingredient. And many, if not most, potions are useful for more than one of those reasons.
 * In Iji, the Resonance Reflector is normally too slow to recharge to be much use for you; you'd be better off blasting the enemies with a BFG instead of trying to reflect their own projectiles back at them. You'd think it would be good for a Pacifist Run (They're killing themselves, right?), only for gameplay reasons the reflected projectiles count as yours, so no it isn't. Then comes the final boss, who has immensely strong armor... and a weapon that does far more damage than anything you've got, and that can be reflected.
 * Version 1.6 changed the reflection mechanic so that deflecting an enemy projectile no longer counts as your kill. Unless of course, it's a projectile they reflected back at you, but with the reflector's load time, you probably won't be able to reflect it again anyway.
 * The Resonance Reflector is an upgraded version of the Resonance Detonator, which is even more useless since it shares the Reflector's absurdly long reload time but its effect is identical to your kick attack (which is always a keypress away and doesn't require you to switch weapons). Kicking also takes a lot less time than charging the Detonator does. The only advantage provided by the Detonator is that it fires instantly when you press the button, while the kick only deals damage about half a second into the attack animation. Enter Tasen Shredders, vehicles that both Iji and the Tasen can use. Most of them spawn with a Tasen rider, but you can kick them off without destroying the Shredder - if you manage to hit a fast-moving vehicle with your foot in the split second before it knocks you down. Resonance Detonators make this feasible.
 * The Tractor Beam spell in Tales of Phantasia is largely useless. In practice, it's supposed to be a useful spell (being the only non-elemental spell Arche can learn for a good long time), but it only works on enemies on the ground. The problem is that many of ToP's enemies (roughly about 1/3) are flying enemies that are NEVER on the ground, while most of the rest are fond of jumping around like rabid monkeys. The result is a spell that so rarely deals damage that most players will turn it off so the computer-controlled Arche doesn't end up wasting half her turns. There's only ONE case where the spell is useful, being in Gnome's Dungeon against the Clay Idol monsters, land-based creatures that take damage from only one attack in the game. Care to guess which one?
 * In Tales of Vesperia, Estelle can potentially give you an item called the "Mother's Memento." It theoretically grants you unlimited healing, as it is never consumed when used, except that the healing it grants per use is incredibly small, and given that any item use in the game comes with a cooldown, there are far more efficient ways to heal. Eventually, you have to fight a boss. Using the Mother's Memento during the battle grants  you the Secret Mission for it, which you can't get in any other way.
 * In Dink Smallwood: Mystery Island, you learn a spell called Duck Magic through a subplot involving a human-to-duck transforming magic fountain. This spell does nothing at all except summon ducks.
 * In Medievil, one of the earlier weapons you get is a wooden Club, which breaks boulders. The Club is unfortunately also the game's only breakable melee weapon, is almost as weak as the Short Sword you start with, and the Warhammer can also break boulders while being stronger, with a longer range and an awesome Ground Pound attack. However, the Club can also be used as a torch, and the Gang Plank Galleon level at the end of the game has cannons with fuses...
 * Final Fantasy VI has the Rasp spell, which eliminates enemy magic points. While stronger at this task than the Osmose spell (the latter also gives you the magic points, saving on Ethers), most players overlook it for spells that do hit point damage - killing things the old-fashioned way. However, there are several enemies (including both iterations of the Atma/Ultima Weapon and literally every enemy in the Fanatics' Tower) that die if all their magic is depleted. On top of that, they usually have Taking You with Me magic attacks; if their magic is drained, they can't do the attack and leave you untouched as they die. And in Atma's case, using Rasp will prevent it from using its most dangerous attacks, which are activated when it has low HP.
 * Then there's Relm's Sketch command, which most people ignore, given that, well, it sucks. However, it's a One-Hit Kill against a few foes. Similarly, you won't use Celes' Runic very often, but there are a few bosses that are significantly incapacitated by it.
 * X-zone is a spell that removes enemies from combat. Like most instant death spells it rarely works on anyone you'd care to kill instantly. It works a lot better if you cast vanish on an enemy first (this may be unintentional), but it also works on the boss known as Wrexsoul, ensuring a quick end to an otherwise annoying boss fight (though you miss out on a reward).
 * Not to mention the Imp status from the same game. Normally it makes you very weak and you don't want to keep it on you, but if you equip the Imp-specific items while Imped...
 * A character that fits this trope is Umaro. He's generally not considered very useful because he's The Berserker and you can never control him. However, that lack of control can actually be a blessing in disguise:
 * Any character you send into the Coliseum to fight ends up being controlled by the computer. This leaves you at the mercy of the AI Roulette, which can be hair-pullingly frustrating as your idiot characters heal themselves while at full HP or cast low-level spells that barely scratch the monster they're fighting. Since all Umaro does is attack, if you send him into the Coliseum he'll actually do very well if you equip him with the right Relics.
 * The Fanatics' Tower messes with your character's command windows so you can only use magic spells or items in combat. Since Umaro doesn't have a command window, he completely ignores this restriction and will simply attack anyway. This can be a lifesaver-when fighting the Magi Master in the Fanatics' Tower, most players will Berserk him to stop him from constantly changing his elemental weakness. Unfortunately, you might end up Berserking him when he's only vulnerable to an element you can't target with your magic. If you don't have a spell like Flare, and you don't have the ability, much less the patience, to use Rasp, the fight can become Unwinnable unless you can find some other way to damage him. Even if he has to do it all himself, Umaro can still destroy the Magi Master for you.
 * Cyan is frequently seen as a Crutch Character because you have to charge up his Bushido attacks before he can use them. You can't input any commands for your other party members until Cyan is ready...but since Umaro has no command window, he can and will attack while Cyan is powering up.
 * Across the Final Fantasy series in general, there are many enemies that trigger Taking You with Me attacks - either machines that self-destruct, or living bombs that blow up when hit with enough attacks. These enemies are, across the board, rather vulnerable to Slow and Stop, which do Exactly What It Says on the Tin, allowing you to take them out without having to worry about them taking out your party.
 * Similarly, the status buff, Reflect can get this treatment. Reflect returns most magic spells back at the caster/caster's party. However, some enemies will cast Reflect on the player's party so that their healing or buffing spells are reflected back at the enemy party. Not only that, but most enemies that use elemental magic absorb what they are casting, thus reflecting magic back at them would just heal them. That is the main reason why Reflect is hardly used by the player, but if enemies cast Reflect upon themselves, the player party can cast Reflect on themselves and cast magic on themselves to bounce it back at enemies without a counter reflect (except for Final Fantasy VII where if the party and enemies have reflect, the spells will keep bouncing back and forth until Reflect fades for someone).
 * Alternately, sometimes you can dispel the enemies' Reflect spells and let them get blasted by their own spells. One particularly funny instance is against the fight against Seymour on Mt. Gagazet in Final Fantasy X, where he tries to bounce a Flare spell off his Reflect barrier to hit you. If you dispel his barrier before he gets the chance, he'll hit himself and then the game will snarkily note that the "Combination Failed".
 * In both Final Fantasy VI and Final Fantasy IX, you can actually cast four spells on the enemies for the price of one. If all your characters have reflect status (through Wall Rings, casting Carbuncle, etc.) and you cast something like a Firaga-All or a Cura-All spell on them, every single one of those spells will be bounced back and hit the enemies. If there's only one enemy, he or she will take the full effects of all four spells at once. So much for That One Boss...
 * The emerald swords of Lands of Lore cause little to zero damage to all enemies and seem to be of no use until you enter the White Tower, there they're pretty effective against the ghosts, who are impervious to normal weapons.
 * In Casper: A Haunting 3D Challenge you collect fool's gold coins throughout the game. Through most of the game they appear useless, until the final boss fight where you have to drop them around to distract Carrigan.
 * Kingdom of Loathing has many combat items that are mostly useless (due to the existence of skills and/or other items that make far superior alternatives), until you reach the final quest. There are 24 different Puzzle Bosses (originally 6 before ascension was implemented, then 12 until the NS13 expansion), of which the game will choose 6 randomly; each one can only be defeated using a specific combat item.
 * There are many other items with similar unexpected usefulness, like the Antique Hand Mirror; using it normally just breaks it and gives you 7 turns of "bad luck" (which does nothing), but using it while fighting the absurdly powerful will kill him instantly. The Chaos Butterfly normally has minor, random effects, or gives a seemingly meaningless message. Yet, not only is the Butterfly one of the special deadly combat items mentioned above, but using it in any combat allows you to complete a certain unrelated quest in half the usual amount of time, if you choose exactly the right multiple-choice options.
 * In Wizardry IV, the most useless summoned monster in the game is also the only thing that can kill the final boss.
 * Wizardry 8 uses as keys for the entrances to Retro Dungeon secret maps cheap starting items quite paltry by the time you get there;  is necessary for one side quest. Many weak potions/powders/etc can be converted into better items via Alchemy skill.
 * Champions of Norrath and its sequel have several spells that either only work on undead, or are much more effective on undead. For example, the dark elf shadowknight's Convert Undead is absolutely useless unless you're fighting a horde of undead. The high elf cleric has several Holy Hand Grenade spells that are only useful against undead.
 * There's a Disney game for the Sega Genesis called The Great Circus Mystery. In it you get several suits that allow Mickey and/or Minnie to solve puzzles, get items and open pathways. You know how you tend to forget about the first one or two weapons you get as the game progresses? Well, nothing will take down Level 5's boss except for the vacuum cleaner-suit from WAY back.
 * Final Fantasy IX has Ipsen's Castle, a dungeon where nearly everything is reversed; stairs and ceilings swapped places and your current weapons actually inflicts Scratch Damage in this area. Most of the treasures you find here are the lousy starter weapons for your party that they came with. While there are no clues on how you can get around the sudden drop in your weapon damage, the castle has crappy weapons because they actually do full normal damage like your more current weapons, due to the castle having the properties of reversing stuff. Luckily, your magic spells are not affected and the reverse properties are only for this dungeon. However, if you are planning to learn abilities while in the castle, you'll be stuck with a party that can't do a lot of melee damage...unless you use special abilities like Throw, Jump, Thievery and Darkside, since the castle's power-reversing actually only affects your Fight command.
 * For Light Side players, the Drain Health Force Power in Star Wars Knights of the Old Republic is near useless for the brunt of the game, handicapped as it is.
 * The sequel had Mira's unique power: while she was your active character, your party wouldn't trigger mines. Normally mines in the KotOR series are widely-spread and easy enough to simply walk around (or through—they don't do very much damage). However, precisely one area in the game, not long after you recruit Mira in the first place, has dozens of mines in thick clusters, entirely unlike the usual arrangement.
 * The sequel also emphasized this with skills through the crafting mechanic. Usually you could rely on your party's skills, rather than your own—and a few, like Awareness and Stealth, were not very useful to begin with. However, they were the basis of the crafting system, and most of the time you were forced to use your own skills when determining what upgrades you could make.
 * Magic: The Gathering in general has many cards that are useless until you find a combo they work in.
 * One With Nothing. Goes from useless to My Hero Zero if you are against an Owling Mine deck (force opponent to draw cards, deal damage for them having too many cards. Was popular enough once that EVERYONE sideboarded One With Nothing) have cards with madness (when you would discard a card with madness, you can play it instead; sometimes for a lesser cost but sometimes for a greater cost); consider also that One With Nothing is an Instant so it can be used even if it isn't your turn.
 * Lifegain cards are almost completely useless, unless you have a card like Yawgmoth's Bargain, which lets you turn life into cards (though you can't draw cards the normal once-per-turn way). Lifegain also became nasty when they began adding specific cards that let you win the game if your life passed a certain extent. Felidar Sovereign springs to mind. Additionally, due to lifegain's percieved weakness, you can gain tons of it for very cheap with a number of black, green, or especially white cards. Then you have certain creatures like Serra Ascendant and Divinity of Pride, which both become ENORMOUSLY overpowered for their costs if you have 25-30 life on hand, and both have the powerful lifelink ability to convert any damage they do into more life. Combine that with an artifact recently spoiled from Innistrad that can tap every turn for 5 damage if you managed to get to 30 or more life and the aforementioned Sovereign...
 * Final Fantasy XI - The two hour ability (a supposedly extremely valuable job specific ability that can only be used every two hours) for Ninjas is Mijin Gakure. This ability kills the Ninja and deals damage based on their current HP. Due to the amount of health enemies have, this ability is basically useless. It does not inflict enough damage to be worth using in any situation where a two hour is justified. There are two uses for it.
 * Avoid the harsh penalty for death, since a secondary effect of Mijin Gakure is to remove all penalties for dying and being raised back to life.
 * A poor man's Warp, since you can return to your home point after you die and again there is no death penalty for doing it this way. This has become less useful due to how easy it is to Warp through higher level spells and items.
 * Fina in Skies of Arcadia has a special move called Lunar Glyph that does a little damage and has a chance of petrifying the enemy. As you'd expect, all the enemies worth petrifying are immune to it...except for one boss that it's almost 100% effective against.
 * In theory, Arrows on Fire are an advanced attack in Trine, doing more damage in return for a bit of magical energy. In practice, normal arrows make up for quality with quantity. However, max-level fire arrows explode to damage nearby targets, allowing you to quickly take out the bat swarms that are hard to hit with most other attacks.
 * StarCraft IIs campaign features one new unit in most missions, and typically the mission revolves around that new unit to a greater or lesser extent. This can make a number of these units Not Completely Useless', though which ones will depend on a given player's style. Battlecruisers, for instance, are generally held to be Awesome but Impractical in terms of resources, but are essential to "Maw of the Void", the mission which unlocks them, since their health lets them weather the environmental effects better than other, more efficient units.
 * * The 'mutate' perk in the Fallout universe. You can re-pick your traits, how grand. Too bad you pick your traits yourself in the beginning of the game and there are few, if any, traits that it would be worth a perk switching to mid-game. Meanwhile, in Fallout Tactics, your team-mates have pre-picked traits, and getting Gifted is worth the perk slot.
 * Some people complain that Kimahri Ronso is redundant because there's no need for a multitasker, but those people forget several things:
 * He can make a useful backup mage or provide additional status effects, which can complement the party member who is supposed to specialize in these things, or even take their place if that party member isn't available;
 * His Ronso Rages can be very useful indeed. Stone Breath and Thrust Kick, for instance, can be used to get instantly rid of enemies that are normally Demonic Spiders;
 * He's the only character besides Auron whose weapons normally have the Piercing trait. This is especially helpful at the start of the game, before Auron actually joins the party.
 * Similarly, Kimahri can be used as a thief as soon as the first level one unlock is found for the Sphere Grid, which is a lot sooner than when Rikku is found.
 * Standard Status Effects are quite handy against the Golden Sun: Dark Dawn Bonus Boss Ancient Devil. Not directly, since like most bosses it's immune, but its major ability, Demon Sign, lets it turn one of your allies against you at any given time, and they can be crippled with status effects. This is useful to keep them off your back without KO-ing them and letting the Devil use Demon Sign on someone else.