Outside the Box Tactic

Sometimes, The Heroes are faced with a seemingly insurmountable enemy. Be it a Mighty Glacier that absorbs damage like a truck or a Fragile Speedster that dodges attacks with lithe grace, some enemies are hard to defeat with standard tactics. They can generally be defeated through brute force, but it's very difficult. The smarter and much easier way to defeat such a foe is to employ clever strategy and some often unintuitive insight.

An Outside the Box Tactic is a simple or otherwise overlooked tactic that is particularly effective against a certain monster or type of monster. It is a closely related to an Achilles' Heel; the difference being that this weakness is not the only reliable way to defeat such a foe. A foe susceptible to an Outside The Box Tactic is still vulnerable to other tactics, but is very weak to this particular strategy. It is primarily a Role-Playing Game trope, but may be found in other types of games as well.

The most famous and common example involves the use of healing magics or other restorative items to harm the undead. Such examples should be listed under Revive Kills Zombie. If this particular application of a technique is the only place where it is effective, it may be Not Completely Useless. May be the result of a bug in the game code. If it's the only way to defeat the foe, it may also be a Guide Dang It. If it's not the only way to defeat a foe, but it requires Forced Level Grinding to defeat it otherwise, it may be commonly thought of as That One Boss or a Beef Gate. Outside-The-Box Tactics are often necessary to defeat a Puzzle Boss or the Final Exam Boss. Contrast Logical Weakness, when it's immediately apparent what needs to be done.

Anime & Manga

 * This can occasionally come up in One Piece, along with unexpected strengths, when a Devil Fruit power sometimes provides an unforeseen advantage against another power. One of the more prominent examples would be low-tier villain Mr. 3, whose power to create objects out of wax ends up temporarily providing the single best countermeasure against poisonous Implacable Man Magellan.

Comic Books

 * In X-Men, Sebastian Shaw absorbs any kinetic energy directed at him, even a bullet, so Storm covers him in snow, which actually saps his energy, due to cold being a lack of said energy.
 * Ironically, 15ish years later the X-Man Bishop—whose powers are similar to Shaw's -- would charge himself up by using snowfall.
 * In Invincible the main character faces a villain with powers similar to the X-Men character mentioned above; the way the main character wins is

Film

 * AT-AT's in the Star Wars series have thick armor impervious to the blasters on rebel fighters. However, due to their being very top-heavy, a simple harpoon and tow cable can bring them down with ease.

Literature

 * In The Wonderful Wizard of Oz, water is this to the Wicked Witch of the West.

Live Action TV

 * Star Trek: The Original Series and Star Trek: The Next Generation used a version of this similar to the Samurai Jack entry below.

Tabletop Games

 * In Dungeons & Dragons, casting Remove Blindness/Deafness on an Eye of Gruumsh (a one-eyed, mad orc fighter) restores its other eye and negates its magical abilities as well.
 * Exalted has a Charm (Order-Affirming Blow) that undoes Shaping effects. Guess what? The Fair Folk use shaping effects to create their bodies. One-Hit Kill.

Video Games

 * Final Fantasy:
 * In the original NES version of Final Fantasy I, Tiamat can be killed with the instant death spell BANE.
 * In Final Fantasy IV, the Wall (Reflect) spell is integral to defeating Asura, who heals herself twice, at the end every round, in addition to attacking your party. The catch? You have to cast Wall on her. That way, when she attempts to heal herself, Wall reflects it heals your party instead. Asura inflicts insane amounts of damage and recovers 2,500-3,300 HP per recovery spell, making her borderline impossible to defeat without this trick.
 * Final Fantasy V:
 * The only practical way to defeat Bonus Boss Odin is to use petrification attacks, which will instantly kill him.
 * The Mimic. He'll attack with whatever you attack him with. The key to victory: Do nothing.
 * In Final Fantasy VI, there is the spell "Invisible". It temporarily causes all physical attacks to miss, but guarantees the next magical attack to hit.
 * In Final Fantasy VII, the Demi spell is surprisingly effective against Emerald Weapon. Demi is a low-level Gravity spell, that does damage equal to 25% of the target's current HP. On most common enemies, it's a waste of time. Most bosses are immune. But Emerald Weapon is not, and, until you whittle his HP down, it can do the 9,999 damage cap to him.
 * In Final Fantasy XIII, bosses are immune to Death... except the final boss, when it's staggered.
 * In the ending chapter of Fire Emblem: Radiant Dawn, the Black Knight can be easily beaten by forgoing use of the Infinity+1 Sword in favor of using a common Hammer.
 * The Berserker in Legend of Legaia can be instantly killed via the Nighto spell. It is the only boss vulnerable to this tactic, and is That One Boss otherwise. It is Fridge Brilliance when one considers that Nighto inflicts the Confuse status.
 * Mario & Luigi: Superstar Saga features the Trunkle boss, which dies to one or two hits of the Chopper Bros. attack to the forehead.
 * Mega Man 2:
 * Mecha Joe walkers are very vulnerable to air shooter and several Humongous Mecha are vulnerable to boomerangs.
 * During the Boss Rush portion of the same game, Metal Man dies to one hit of his own weapon.
 * The Mega Man X series continues the trend of its predecessor series. While many bosses have Logical Weaknesses, the Launch Octopus and Flame Mammoth both have one of these - the boomerang attack can cut off Octopus' tentacles and prevent him from using his homing and tornado attacks, as well as being able to cut off Mammoth's trunk so he can't throw around globs of oil he can set on fire and turn them into pillars of fire. You can also stunlock Spark Mandrill and Sting Chameleon.
 * In Moria and some versions of Angband, the spell "Turn Stone to Mud", normally used for digging new passages, can also be used to devastating effect against stone-based monsters such as golems.
 * It's a running gag that the final boss, Dhaos, of Tales of Phantasia is susceptible to the Indignation spell. In cameo appearances in later games, he dies to one use of the spell.
 * Gespent, a sub-boss in Wild ARMs 3, can be killed with a single use of the Requiem spell.
 * Get the hit just right, and it's possible to One-Hit Kill the final form of The Legend of Zelda Links Awakening's final boss with the boomerang.
 * Several enemies in Metroid Prime 3 can be killed in a single strike of the Nova Blaster augmented by the X-Ray Goggles, due to the limitations of their Phazite armor.

Visual Novels

 * In Fate Stay Night, Saber is representative of . She is vulnerable to items and spells that harm as a result.

Western Animation

 * Justice League Unlimited
 * In the episode "Hawk and Dove", the Annihilator defeats much of the League by feeding off aggression and hostility. When Dove faces the machine and neither attacks it nor fights back in self defense, the machine shuts down.
 * In the same vein, the android AMAZO mimics both the principal characters' superpowers and weaknesses. After he obtains Superman's strength, he also obtains his weakness to kryptonite. He quickly evolves past this weakness though.
 * The Samurai Jack episode "Jack vs. Mad Jack" has Jack fighting a clone spawned from his irrational anger. At the conclusion, he catches on, steps back and meditates. With his anger calmed, the clone's power cuts off and it dissipates.