Tactical Suicide Boss

""I-have-no-will-to-live-so-here-is-my-weak-spot-please-shoot-it Boss Battles""

- Yahtzee, Zero Punctuation

In video games, it's quite common for a boss to only be vulnerable at a particular time. It's one thing if it's due to the boss needing to catch their breath every so often or the like. But sometimes, it's just because a given attack leaves them open. Maybe it exposes a Weak Spot while preparing the giant laser, maybe their attacks double as weapons or platforms that the player can use to reach their target, maybe on occasion it decides to just stand there laughing at you with its defenses down, or maybe it will keep charging head on into walls until it dies.

This is a specific form of Hoist by His Own Petard - the boss only has to avoid one particular action to be literally invincible. Since it involves the boss intentionally leaving themselves open, it also heavily involves carrying the Villain Ball. Finally, Fridge Logic heavily comes into play - it's usually in retrospect that you realize What an Idiot! the boss in question is for continuing to perform the attack even after it's been exploited several times. With animal bosses or others too unintelligent to realize their mistake, this can be justified, and to an extent it can make sense with robotic bosses as well, but in that case you have to wonder who designed and programmed them...

Hopefully, sooner or later there will be a variant of this where the boss does stop using a particular move that leaves it open to attack... only to then use a different move that also leaves it open to attack.

Bosses like this can occur with any of the three types of AI (as described in Artificial Stupidity)
 * AI Roulette: by far the most common for this trope. It will use one of several attacks randomly, but only a fraction of them (often just one) leaves it vulnerable to damage. Since the length you have to survive for is dependent on how often the boss makes the suicidal attacks, the fight is partially a Luck-Based Mission.
 * Set Pattern: The boss has a fixed cycle of attacks, and at some point renders itself vulnerable.
 * Analytical/Responsive: The boss will make itself vulnerable if given a certain situation. If the boss was run by a smart analytical AI, it would only use the vulnerable attack as a last resort, when no safe attack is possible (possibly not even then, if the boss doesn't care about letting the player live). But usually Artificial Stupidity is applied deliberately to prevent the game from becoming Unwinnable, especially if the boss always has safe attack options available. Alternatively, there may be a Tactical Rock-Paper-Scissors system where the boss defending itself from one kind of attack leaves it vulnerable to another, forcing the player to work out the right Combos of attacks to defeat it.

When it comes to video games, Deadly Dodging is nearly a sub-trope, as is Tennis Boss. Sister trope to Attack Its Weak Point. See also Boss Arena Idiocy.

"It's sort of like a birthday party, except... The exact opposite. Let's start handing out the presents... *gets on his hoverboard* This is from Tiny. *throws a bomb* This is from Dingodile. *throws another bomb* Ripper Roo, you shouldn't have! *another bomb* Pinstripe, how thoughtful! *and another* Oh dear, two of the same! *throws a final bomb and starts charging his ray gun* Here's one gift you can return! *fires*"
 * Portal justifies/lampshades this trope. The boss fight starts once you destroy GLaDOS's morality core, which prevented her from trying to kill you with neurotoxin. GLaDOS notes that a side effect of the destruction is that she can't turn her self-defense rocket turret off anymore. The turret, of course, is necessary to beat her, by redirecting the rockets through portals.
 * Portal 2: When you confront GLaDOS again, she's taken care to keep you from using the same tactics to beat her as in the first game. However, unbeknownst to her, you've already sabotaged her defenses.
 * Mostly subverted during the true final boss battle, the boss informs you that it has analyzed the first game's climax and set up an arena with no portal surfaces and shields for itself... but left a conversion gel tube nearby to make some portal surfaces. After each time you hurt the boss, though, it reorients its shields to protect it from whatever tactic you had to use to hurt it last time. However, after taking some damage it informs you that it also cannot shut off the bombs now that it's recognized it as a liability.
 * Super Mario Bros.:
 * Super Mario Bros: Mostly Boss Arena Idiocy, placing an axe at the end of his bridge even after seven fakes fell to their doom. But for this trope, his habit of making big slow jumps in the air can be incredibly helpful to the player, especially in later worlds.
 * Super Mario Bros 2: Wart opens his mouth so you can feed him veggies that kill him. To be fair, it is basically his only move. That doesn't excuse putting his own personal Kryptonite-dispenser right in front of him, though.
 * Which is actually the Dream-Making machine-thingamajig, which is self-aware and chooses to help Mario.
 * Super Mario Bros 3: Bowser will keep ground pounding at Mario, even if it means his death.
 * Super Mario World: If Bowser stopped throwing Mechakoopas after Mario, there'd be no way to defeat him.
 * In New Super Mario Bros Wii, if Bowser just restricted himself to smashing the foundations of his castle and not fire breathing, blowing out passages, he would have killed you.
 * Hell, this goes for almost every boss in the game. If they would keep spinning, Mario and company would eventually tire themselves out. The only exception is Iggy and Ludwig, and only the second time you encounter them (Iggy cause he just gets stunned and Ludwig cause he's stuck on a small platform while doing so), as well as bowser jr., who has different reasons for his screwups.
 * In Super Mario Galaxy, if Bowser just restricted himself to breathing fire and spinning around in his shell, you'd have no way to defeat him. Thankfully for the player, he'll also jump at you, even if you're standing on a thin layer of glass which is right above a lava pool... which is the only thing that can damage him.
 * In Super Mario Galaxy 2, if Bowser would just refrain from Megaton Punching the planet and launching those meteors into the sky, you'd have no way to defeat him.
 * And also non-final bosses: in Super Paper Mario, if Blooper never raised the tentacle with the red suckers, it would never be able to be hurt.
 * Another from Super Mario Galaxy 2. If Megahammer never fired Bullet Bills at you, to be licked up by Yoshi and shot back at its weak points, it'd be untouchable in spite of the Boss Arena Idiocy inherent in having both Yoshi eggs and Sling Stars sitting around.
 * Averted by, of all things, Baby Bowser in Yoshis Island. About the worst thing he does is get too close to Yoshi, making it easier for himself to be hit; other than that he doesn't do anything that contributes to his defeat.
 * A few dozen bosses in Gradius and R-Type - if you are only vulnerable when firing a particular laser (especially when you can destroy the player by ramming them), don't fire the laser.
 * In No More Heroes and to a certain extent No More Heroes 2 Desperate Struggle, if you think about it, most of the bosses are actually completely invincible most of the time (the most obvious exception is Dr. Peace). There are usually only small windows of opportunity where the boss is actually vulnerable to your attacks; learning when these windows appear and exploiting them is pretty much the only way to win the game.
 * The Legend of Zelda a Link To T He Past:
 * Agahnim
 * Only one of his three attacks can be reflected back to damage him. If he never used it, he'd have succeeded in taking over Hyrule.
 * As Dethl's Agahnim form is a deliberate recreation of said fight, this also holds true in Link's Awakening.
 * The Agahnim clone in Oracle of Seasons can be killed this way, but since he's vulnerable to the sword that time it's not the most efficient method.
 * A LOT of bosses that do this: King Dodongo (keep rolling, don't spit fire), Ganondorf (almost every single fight, he shoots an energy ball that you two end up smacking back and forth; spam your un-reflectable powers), Molgera (dude.... seriously? Sticking your tongue out and just sitting there?), Morpha (just stay under the water, don't make yourself an obvious Clawshot target), Koume and Kotake (stay on the other side of Link when he's reflecting the ice/fire magic, don't fly in front of it; alternatively, aim at the ground beside him for Splash Damage Abuse) and others that I'm blanking on right now.
 * In Oracle of Seasons, Onox, the final boss is this in his third phase:
 * The many-armed swordslinging robot in Skyward Sword can only be damaged by his own swords. He'd be unbeatable if he didn't keep swinging his swords into the floor so violently that he gets stuck, allowing you to rip his arms off, take one of his swords, and beat him up with it.
 * Kirby's Dream Land:
 * King Dedede has these attacks which makes stars appear. If he never used them then Kirby wouldn't be able to spit the stars at him. (But in the later Kirby games, Kirby can simply bring along a special power and pummel him.)
 * Virtually all bosses and sub-bosses in the Kirby games have at least one attack that causes an inhalable object to appear, most often a star. The only exception is Meta Knight in Kirby's Adventure, since the player was given a permanent Sword ability for that battle. Meta Knight himself gave you the sword, but he has his reasons for that.
 * there is one boss from Just Cause that decides to attack you with a Kill Sat that shoots missiles. while standing on the same narrow rooftop as you. to quote from Zero Punctuation "didn't even have to shoot the stupid bastard. would have practically been assisted suicide."
 * Sonic the Hedgehog:
 * Many of Robotnik/Eggman's machines are like this, especially in the later games, where he has attacks that can hurt Sonic without going into harm's way, but he does so anyway. He has an IQ of 300.
 * Sonic & Knuckles's True Final Boss is a specific example; its first phase can only be undone by its own heat-seeking missiles.
 * An interesting aversion in the same game. Knuckles's final boss, Mecha Sonic, charges itself up with the Master Emerald. It's invincible, but the charge eventually fades away, making it temporarily vulnerable while it retreats to the emerald to recharge. Later on in the fight, it starts to look heavily damaged, and can't maintain the emerald's charge, forcing it low to the ground while hovering right in time with the invincibility fading away for a moment...
 * The Flying Battery miniboss, from Sonic & Knuckles, can only attack you with its oversized spiked flails. It doesn't try to think up a better way to deal with blue hedgehogs on its head other than bashing its own head in. Even assuming that it's not mechanically capable of low lateral swipes over the top of its head, it would still be able to win by doing nothing, thus keeping Sonic busy long enough for Robotnik to finish carrying out his evil plan.
 * Yet another unique example from Sonic & Knuckles: The Lava Reef Zone boss. Eggman will shoot spike balls that ultimately drift into his own ship.
 * Still the same game: Death Egg Zone miniboss. Completely invulnerable to a direct attack, but vulnerable to its own minions hitting it from below when you flip the gravity.
 * The Egg Viper from Sonic Adventure. During the first part of the fight, Eggman regularly uses a charged laser attack that requires him to hold still with the cockpit wide open for several seconds; most players will never even see him get to the actual attack. He later switches to a slightly more direct attack that involves shooting a very platform-like projectile that Sonic can easily ride straight back for the hit.
 * Also, E-101 MKII. He simply bats away all your shots or strafes out of the way, but completely exposes himself every time he attempts to impale you. If he never charged, he'd be invincible.
 * The Egg Hornet. If all Eggman ever did was shoot those little missiles at you, and never stuck himself in the ground trying to hit you with his ship, Sonic would wear out and eventually get hit.
 * Chaos isn't immune: in his 2 form, he bounces around as a giant ball in one attack, and covers most of the floor for a couple of seconds in another. Why would he ever need to do that stretch-punch thing? Well... because if he didn't, he couldn't stop moving afterwards, giving Knuckles a chance to punch his brain.
 * And his 4 form is worse; the only time he's vulnerable isn't. Associated. With. An. Attack. If he'd stop just surfacing and sitting there, Sonic, Tails, or Knuckles would eventually lose.
 * Chaos 6 has this problem as well, though to be fair it's not chaos's fault this time but rather eggman's, if he wasn't flying around dropping bombs then chaos would have been impossible to beat, if only eggman had the sense to stay out of the fight.
 * Iblis from Sonic 2006. Silver had to kill it by reflecting its thrown rocks back at it, preferably before it managed to close the distance and slam the platform three times and drop you to your death. Unfortunately, his AI Roulette made it possible to reflect every rock he threw, and still die at the end because he spent so much time throwing shockwaves that you couldn't do anything with. This actually happened to Pokecapn in the infamous Let's Play of the game.
 * In Knuckles Chaotix, what stage the player goes to next is determined by a roulette-like device with an image of each of the five stages on it. As each stage is complete, the images are replaced with 1, 2, 3, X, and 4; once all five stages are completed, the roulette is used to fight Metal Sonic. Whatever number the roulette lands on during the fight determines the attack, but landing on the X causes damage to Metal Sonic. To Metal Sonic's credit, when there's only one number and the X left, X causes the attack and the number defeats him, in case the player is able to time the roulette at that point.
 * Sonic Rush:
 * It has bosses like this that use AI Roulette. The programmers were considerate enough to actually adjust the time bonus based on when the boss made itself vulnerable. If it did another move, the time it used up didn't hurt your time bonus.
 * While the Ghost Titan is already one of the most frustrating bosses in all of Sonic history, this Sonic Rush Adventure boss would be literally invincible if he'd just stop shooting and only punched.
 * Punch Out:
 * King Hippo. If he never opened his mouth, he'd literally be unbeatable.
 * In the Wii version, interestingly, this wouldn't save him -- hooking his stomach when he jabs gets you Stars, and Star Punches will hurt him mouth open or closed.
 * Everybody would have a better chance against Little Mac if they didn't have tells, stop to taunt, etc. Of course, they do recognize this in time for Title Defense mode, shoring up some of their vulnerable spots (and sometimes opening up whole new cans of this).
 * Okami:
 * Orochi
 * He is only vulnerable after you get his various heads drunk. You do this by drawing the sake below him into his mouth when he roars, and he roars after you thwart his attacks. You'd think he'd figure out to keep his mouth closed. Furthermore, you can only truly damage him after knocking out all eight of his heads, which only stay down for a short time. Nearly all the other bosses in Okami fit this trope as well. At least mythology establishes that Orochi is an alcoholic, justifying his inability to stop drinking sake.
 * It gets better though, because Orochi manages to turn himself into a case of Too Dumb to Live: You fight him times, and each time he uses the 'Attack-'n-Roar' technique. You would think that after !
 * Also, Ninetails. In the first part of the battle, drawing lightning to his sword when he lifts it up for a charged attack is the only way to make him vulnerable.
 * In American McGee's Alice, the Voracious Centipede is invulnerable to attacks, except for an old scar on its underbelly. It is usually hidden but can be targeted when the Centipede is rearing for a body slam attack.
 * In the tower level of Dynamite Headdy, Trouble Bruin can only be hurt when he moves himself toward you (as opposed to his other move, destroying a section of the tower). It's not clear whether it's totally random or if looking away from him helps.
 * Donkey Kong Country:
 * King K. Rool is invincible... until he throws his crown at the Kongs, which allows them to jump on his head and hurt him. He repeats that move 10 times in the battle.
 * K. Rool in Donkey Kong Country 2 shoots spiked cannonballs at the player, but will sometimes shoot out an ordinary cannon-ball which can be thrown back at him to jam his gun. Nine times. (Ten if you count the True Final Boss). He's even dumber in the third game.
 * In 3, he's more a case of Boss Arena Idiocy ; you can only damage him with barrels, which are dropped into the arena from levers. Kaos and Barbos from the same game are straighter examples; Kaos' blade spin attack does nothing except provide a handy platform from which to jump on him, and if Barbos didn't send his minions after you, or launch homing missiles, you'd have no way to damage his shield.
 * 64 makes it even worse. For example, when fighting him with Tiny Kong, he will repeatedly butt-slam the arena to cause shockwaves. Eventually, his ass gets too sore to keep doing it and he moans in pain for a while, leaving him wide open to attack.
 * Some bosses in Fraxy will flip open to expose their weakpoints after some time, then close them again. Some attacks are also tuned to start when this happens, so watch out!
 * Shadow of the Colossus:
 * Almost every boss features this. If the second one didn't try to stomp you, you couldn't shoot its feet. If the bird didn't dive bomb you, you couldn't climb onto it, etc.
 * It's a rare justified example and a bit of Fridge Brilliance, as throughout the game it's implied that the Colossuses (Colossi?) are, at heart, innocent and child-like creatures trying to defend themselves. They couldn't understand that they're leaving you a chance to attack -- they're either naive or territorial, and either way they're scared. Though there are a few... exceptions.
 * Metroid:
 * If Kraid would keep his mouth shut he would be invulnerable. If Metroid Prime would not squirt out pools of pure Phazon, Samus wouldn't be able to use the only weapon that works against it. If Phantoon would stay phased out and shooting at Samus instead of periodically materializing in the middle of the arena, he'd be untouchable.
 * Phantoon may not be able to stay phased permanently - it may be like how whales have to surface every so often to breathe; they'd never get harpooned if they just stayed deep underwater, but it isn't possible.
 * Mogenar from Metroid Prime 3 can only be damaged by using the Hyper Beam to destroy the sockets on his body... which means you have to blow up the red orbs inside the sockets first... of a boss whose tactical stupidity is resorting to the charge attack that lets you shoot the orb on its back.
 * Remember that Samus could force Kraid to open his mouth by shooting his eyes, something he can't close if he hopes to win. Metroid Prime probably needed to vent phazon to avoid Phlebotinum Overload, and Mogenar, being a corrupted magically powered mecha, is probably an idiot.
 * The final boss of Metroid Prime 2: Echoes, Dark Samus (of course), combined this with an irritating caveat. Requiring the player to absorb the smaller Phazon attacks was understandable, and the Scan Visor even explained such. What it didn't say is that, in order to do this, you need to stand still - in an action-adventure/FPS hybrid during a boss fight.
 * The final boss in Skyblazer. If he didn't try to punch you with his massive arm that you can use as a platform, you'd run out of magic far before he'd take enough damage to die.
 * Crash Bandicoot:
 * Oh, Cortex. Why do you bother shooting at with green lasers that can be spun back at you, when you could simply have continued with the red and blue ones that couldn't? Also, lowering your energy shield at the same time you blow open a hole in the floor with mines is just asking for it, really...
 * That's not the end of it, although Cortex is the only one who purposely uses it. Koala Kong throws rocks a you, but he gets so tired that the third one lands in front of you, where you could spin it back. Then we have N. Brio, who eventually drinks a Super Serum that turns him into a powerful mutant. However, while attacking you, hitting the ground with his hands causes a block to fall from the ceiling, letting you jump on his head.
 * The Komodo Bros. in the second game. Had Moe just kept throwing his swords at Crash instead of sending Joe spinning around after him, the latter wouldn't get himself dizzy for Crash to send him bouncing back into Moe.
 * In the third game Tiny wouldn't be vulnerable if he kept trying to stomp on Crash instead of using his trident, Dingodile should've just kept shooting fireballs into the air instead of destroying the crystals around him, and is there any particular reason at all why N. Tropy creates a trail of platforms leading to him when he becomes exhausted?
 * Tropy's mistake is repeated again at the end of N-Tranced.
 * In Crash Twinsanity, Cortex not only uses three attacks, only one of which you can deflect, but he actually tells you how to beat him.


 * The bandit king in Fable has an attack where he stabs the ground, usually when the player is standing right behind him. He's invulnerable at all other times.
 * Early on in Nicktoons Unite!, you meet ghost prison guards who are intangible except when attacking. There's also similar fighters later on, but Danny gets the ability to turn intangible himself and is therefore able to hurt intangible opponents.
 * Final Fantasy VII:
 * The first boss in has a defensive mode where it counterattacks any attack by the character with severe force. Why it does not spend the entire battle in this form is unknown.
 * It knew about the translation error that inserts an egregious Cue Card Pause making it seem like it's instructing you to attack in that form -- the last part of the message that tells you not to comes later, after an exclamation point.
 * In fact, all four of them are meant to get the player, who may be used to Turn Based gameplay, used to the Active Time Battle system, especially the idea that the battle continues, and the boss continues to act, even if you don't, and that sometimes you'll need to wait.
 * In regards to Whelk, staying in its shell for the entire battle doesn't make it invulnerable, it merely takes a lot longer to destroy it since the shell has 50 000 HP. It's even possible to ignore the warning to not attack the shell since its MP is very low and healing the party is easy despite the powerful Counter Attack.
 * You even get a slightly more useful drop (A MP recovery item as opposed an HP one) if you kill the shell. Later on you can pull a similar trick with a stronger Palette Swap to get two of the items it drops.
 * As for the Wing Raptor, it's actually completely defeatable in guard mode, but it counter attacks viciously if attacked.
 * Iji:
 * Most notably, Asha, who can dodge absolutely anything, but thinks that dodging weak weapons is cowardly, even when he's about to die. Another boss, Iosa, is exposed only after you duck one of her attacks (granted, you only need to take advantage of this once) - which she uses, even though she also has attacks that don't leave her exposed. And the final boss, in order to charge up his most powerful attack, chucks incredibly powerful blasts at you... which can be reflected.
 * In an inversion, other assassins will use a move more frequently if they have successfully damaged you with it, and avoid moves that you hurt them with.
 * Noitu Love lives and breathes this trope, with nearly every boss in the game opening themselves to attack or have a explicitly labeled weak point. Actually all of the games made by the author revel in this trope. As seen in this review of all his games.
 * However, justified in the boss O2/Joy, who has to be deliberately provoked into doing his tactical suicide attack.
 * The Metal Queen in Brutal Legend, a giant spider. Possibly justified in that a wild animal would take more than a few hits to be trained into not using that attack.
 * Amorphous:
 * The Gray, which normally will harden in reaction to your attack. Its main attack, a steel-like tendril, leaves it unprotected until it is retracted.
 * The Horror, which is essentially the Gray on steroids -- basically, a living buzzsaw that your sword bounces off of (leaving you wide open to being shredded). However, at certain points it fires out four flying saw blades, which again render it immobile and vulnerable until they return.
 * The Void Eater is only vulnerable when using its beam attack. Trying to attack it at any other point (or even getting close, for that matter) well result in you getting splattered all over the screen. If you attack a mobile black hole, you deserve exactly what you get.
 * The Razor Queen is only vulnerable to attack after it charges you
 * In the SpongeBob SquarePants video games Battle for Bikini Bottom, The SpongeBob SquarePants Movie and Truth or Square there is at least one boss that does this. In BFBB every single boss does it except for the final boss's second form. Sandy Robot should stop using her Ground Pound move, and kick the player's ass with the "clothesline" move. And Patrick Robot is a real idiot in spinning around until he gets dizzy. King Neptune should stop using his easy to dodge sniper move. Also the giant Plankton in Creature from the Krusty Krab deserves a mention. He just stands there with his HANDS on the buildings waiting for you to hit them.
 * Alien Soldier has the giant moth Bugmax. It frequently uses a move where it drops caterpillars that provide health when destroyed. Your character has a very damaging fiery dash-teleport that can only be used at full health, after which he will need to get more as the attack is Cast From Hit Points. You know where this is getting already.
 * Nigel Block in 007: Agent Under Fire, both times. If he didn't drop his rocket launcher in the final battle all he'd have to do is float there with his jetpack until the withdrawing floor beneath you finally collapses and drops Bond into the pit. Earlier, he'd have been invulnerable if he hadn't called in the mooks that helpfully provide you with the rocket launcher when killed, nor would there have been a problem if he had chosen not to stop the fans protecting the air vents above the geothermal power station. On top of this, Bond never would have been able to locate and destroy had Bloch not shoved him into the pool that leads to it and instead shot Bond in the head while he was Distracted by the Sexy.
 * Parodied in Sluggy Freelance where, when fighting a giant monster, Torg ignores the creature's giant eyeball altogether, instead focusing on the fact that, "It lifts its belly every minute or two! Go for the soft, occasionally revealed, underbelly!"
 * Most of the monsters on Monster Hunter series do this in some way or another. Either by exposing some weakpoint before (or after) their attacks or by sticking themselves into somewhere.
 * The final boss of Chip 'n Dale: Rescue Rangers 2 drops bombs on the ground every time he flies into the air, which the player must then throw at him.
 * Actually, six out of eight bosses in this game are this, providing you with vital projectiles (and the other two are victims of Boss Arena Idiocy), but it's the final one that takes the medal. It's a bit better that his bombs are timed and have to be thrown at a precise moment... until you figure that if you do not touch the bomb at all, he probably will ignorantly land on top of it, letting it detonate directly under his bottom and hurt him. So, a somewhat skilled player can just dodge his attacks and watch the Final Boss literally commit suicide, all by himself.
 * It would be easier to list An Untitled Story bosses that don't stop in their tracks and practically yell "HIT ME! HIT ME!". Well, there are two such bosses.
 * Two of the Bonus Bosses in the flash RPG Sonny do this. Omen has a move that makes both his next attack and yours much more deadly; if you already have a shield in place, you can hit him For Massive Damage while absorbing his attack. Dr. Herregods is even more egregious; he has one million hit points, and once you've knocked off a thousand or so he will heal himself for two million hit points.
 * Unfortunately, Real Life military tacticians and prizefighters do this sort of thing all the time. Examples will be omitted to avoid offence - think of your own favorite.
 * Subverted by Zeus in God of War 2. The fight has two different stages. First, Zeus is giant and you can't directly attack him. However, he summons sirens that release a deadly shockwave when you kill them, which damages him. The other stage is Zeus shrinking and fighting Kratos straight up. After awhile, Zeus remembers that he's the freakin' king of the gods, and starts bombarding Kratos with an endless stream of lightning. Kratos has to trick him to beat him.
 * World of Warcraft:
 * Both C'thun and Yogg-Saron, the game's resident Eldritch Abominations, employ attacks that swallow or consume players, but also place them in a location where they can inflict damage on the normally invulnerable boss.
 * Icehowl in the Crusader's Coliseum, is a Bullfight Boss who literally charges into walls and stuns himself. Possibly justified, as yetis aren't all that smart.
 * Hakkar the Blood God drains the life from the raiders, healing himself to nearly maximum health. However, all over the arena there are winged serpents that leave a cloud of poison when they die. If the players poison themselves, Hakkar drains the poison from their blood.
 * Ys 3: Oath in Felghana. If  didn't use That One Attack on you, you'd never kill him, as he is invincible until he uses that dash stab attack of his. He's got plenty of other attacks to murder you outright (especially the 2nd time you fight him...), he clearly doesn't need that Dash Stab, complete with the "HIT ME NOW" sound effect that also telegraphs he's about to do that move.
 * Similarly, Ernst in Ys VI will usually hit you first when you get close, but takes a moment to recover from his dash attack.
 * In Teenage Mutant Ninja Turtles Turtles in Time, the stage four boss is Shredder himself manning a Spider Tank. The turtles can't hurt the mecha directly; they have to throw Foot soldiers at it. If Shredder stopped sending his mooks in, he would have all the time in the world to simply pick the turtles off with his guns. To be fair, at least the exact type of mooks you have to use as ammo changes with the difficulty level: easy has the normal variety, normal has the ones that throw shurikens and hard has the variety that block most of your attacks and can only thrown reliably by hitting them with a running tackle first, which can be tricky to connect with.
 * Almost all of the bosses in Billy Hatcher and the Giant Egg do this, with most of the bosses all you have to do is dodge everything until they mess up and become vulnerable, sometimes the bosses do the dumbest or just clumsiest things to allow them to be harmed.
 * Several bosses in Mega Man Legends are guilty of this - and most of them are piloted by, guess who, the Bonnes. Teisel's Marlwolf hurls powerful homing blasts, but every so often he'll turn away and open up a small hatch where the armor is thinner. His Servbots use it to lob hovering explosives; judging by Teisel's repeated howls of CLOSE THE HATCH!!, it just doesn't occur to them not to.
 * Both bosses in World 1 and World 2 of Fancy Pants Adventures suffer from this. The penguin is a Bullfight Boss who will always get his horns/flippers stuck in the wall, allowing you to jump on him. The rabbit, on the other hand, cannot be defeated by jumping on him at all, yet he still jumps high and drops spiders on you, though a snail always drops with them which can be used to beat him. To make matters worse, kicking him after hitting him with a snail shell will make him almost immediately use the same move again (with several more spiders, admittedly).
 * Though Golem's core in Bayonetta can be attacked any time the boss itself is attacking, only a few of its forms allow you to activate Witch Time. This is not a problem mostly, except during a timed challenge mission where the boss can only be hurt during Witch Time. During that mission, you are entirely at the mercy of fate whether it decides to use the two attacks that leave it vulnerable.
 * Both bosses of Iron Canopy in Darksiders are of this variety. The Brood Mother has a sucking in air "attack", which doesn't actually do anything but let you feed her a tasty morsel to give you a shot at her vulnerable backside. The boss of the area, Silitha, will occasionally interrupt her Teleport Spam to stand briefly still and taunt you.
 * Sardius in the SNES game Super Ghouls 'N' Ghosts; he can only hurt you with a Beam Spam attack from his mouth, and whenever he does so, he also creates magical platforms that raise Arthur up so he's level with Sardius' weak spot, his head.
 * Psychonauts:
 * The Brain Tank and Kochamara bosses have the most blatant cases of this. The former's only weak spot is its underside, which it reveals for a looong time when rearing up for a charge attack, and the latter has an attack that drains its shield into a weak beam-thing that you can reflect back or dodge while blasting him.
 * If the Butcher never did a single vertical slash his arm would never get stuck in the ground, giving a way to reach his head. If didn't throw spiked flaming bowling pins at you during the second fight you'd have no way to damage the Butcher in the second battle.
 * The Star Wars Customizable Card Game features this for the second Death Star. A card called That Thing's Operational lets you move your Death Star and blast capital ships with it, but it also means that, when not around Endor or if the shield's not up, your Death Star is vulnerable. The light side player doesn't even have to play another card!
 * Parodied in The Simpsons Game, where the Simpsons discover they're in a video game and use this knowledge to their advantage. Unfortunately, Genre Savvy comes back to bit them in one battle against aliens, when Bart points out that the UFO fires four times and exposes its weak point. The aliens immediately start to wonder why they do that, and resolve not to do so anymore, making them completely invulnerable as they rampage through Springfield.
 * In the final fight of Mega Man Zero Dr. Weil can only be hit when his core is exposed to attack. If he waited the two minutes without attacking he'd be able to destroy Area Zero without Zero messing up his plans. Then again, he is a vengeful, hateful psychopath and touching down on Area Zero would destroy him too, so he's probably getting what little satisfaction he can get in seeing Zero die before him before he gets turned into a giant crater.
 * Gate, one of the last bosses of Mega Man X6, is normally completely invincible to your attacks, but to attack you he throws energy balls that can have one of several different effects. When you destroy these, their pieces scatter in six directions, and they can hit Gate to damage him. At low enough health he will eventually start using a purple slash that can temporarily destroy the platforms you have to stand on, but he won't stop throwing energy balls. And to think, usually the series' fortress bosses are ordered from least to most interesting...
 * Nie R's Defense System Gepetto, robotic guardian of the Junkyard, has the following attacks: fire a continuous laser stream from each fingertip, fire homing missiles, slam its floating hands on the Boss Arena, spawn endless robot drones with lightning and magic bullet attacks, a gigantic mouth laser, and... spawn bombs. Not armed bombs, just bombs. Which just sit there until you grab one and toss it. And it spawns them immediately before opening its mouth to charge up for the giant laser. Even Grimoire Weiss cracks wise at "such an obvious weak point."
 * Medi Evil 2:
 * The Tyrannosaurus Wrecks has an attack where he simply stands still and summons two baby dinosaurs to attack you. This is Dan's cue to Attack Its Weak Point.
 * The Count suffers from both this and Boss Arena Idiocy; he starts the fight using attacks that can be reflected back at him with mirrors, before switching to full-on Boss Arena Idiocy (you have to use the mirrors to burn him with sunlight).
 * The Ripper will sometimes stop attacking Dan in order to attack Kiya instead. This is the only time Dan can damage him.
 * When fighting Palethorn's Cruiser, the only time it can be damaged is when it flies past firing missiles, allowing Dan to get behind it and Attack Its Weak Point. If Palethorn only used his machinegun attack (which lets him stay at one end of the arena), he'd be unbeatable.
 * Star Fox 64:
 * Some bosses will attack you with weapons that can be destroyed and converted into collectible bombs, even if bombs are the boss's only weakness, and without a constant supply you would quickly be left helpless. One boss attacks by constantly shooting floating barrels. It's almost impossible to be hit by these barrels, but they can be shot to yield health-pickups.
 * In addition, Star Fox 64 has a boss that is quick and manuverable. Since he's one of the few bosses that can be hurt without attacking a weak point, those are its greatest strengths. And every so often it flies to a platform in the middle of the arena and just stands there shooting at you, making it an easy target.
 * Spyro the Dragon is full of this. In the first game, Doctor Shemp would have lived if he didn't expose his back when he attacked, and Metalhead combines this with Boss Arena Idiocy; he could have easily stayed in the first area after you destroyed his power poles and would have been invincible. Second game, to defeat Crush, you need to attack him, then let him bring the ceiling on himself. It's somewhat subverted, as the rocks can hurt you also. Halfway subverted when he uses that against you, chasing you for a bit before smashing the ground. Third game, ALL THE BOSSES. The first four deserve special mention, as your ally helps you to hurt the boss. Of course the boss doesn't pay attention to the powerful kangaroo, the flying penguin, the yeti or the laser-gun armed monkey.
 * Metalhead may be somewhat justified in leaving the first area; since those poles are power poles, he may require them to operate at a combat-capable level.
 * Gears of War 3:
 * The Lambent Berserker would be all but invincible if her ribcage didn't open and expose her glowing imulsion core whenever she charges, which she does a lot.
 * In the third game's DLC "RAAM's Shadow", General RAAM would be all but invulnerable if he would stop deploying his Kryll shield to attack the humans, instead relying on his blade (which the player can do during the segments where you play as him) or stalling until the Kryllstorm claimed them. In 1 (chronologically later), he smartens up and carries a Troika, which is why he is That One Boss.
 * In Treasure Adventure Game, several bosses suffer from this. However one robot subverts it: once you've attacked it twice when it exposes its weak spot, it changes its programming to not expose it any more.
 * The Ceaseless Discharge in Dark Souls can be easily baited into trying to leap at you over a huge pit. Attacking the arm it uses to keep from falling kills it immediately.
 * The Ninja Gaiden remakes usually make you work for your attack opportunities, but one notable example in the first game -Marbus- fights by flooding the area with some mooks and then taking potshots at you. While you can, if you're lucky, knock him out of the air on your own, he also tries to swoop down at you, invariably giving you a chance to beat the stuffing out of him.

Non-videogame Examples

 * Magic: The Gathering features a number of cards like this. Lich, Final Fortune (and its many reprints under different names), Nefarious Lich, Phage the Untouchable, Immortal Coil, and the Pact cycle will all kill you under the proper conditions. The trick is to win before those conditions are met.
 * That or use certain other cards in conjunction with those cards. (Hive Mind, I'm looking at you and the Pact cycle.)
 * The Omnidroid machines in The Incredibles can only be hurt by their own arms. That said, the new model is smart enough to not attack itself voluntarily.