This is when a hero, or a top-billed friend of theirs, seems to be doing absolutely great in a fight — no enemy even so much as grazes them— only to suddenly get an unlucky stab/shot get through their seemingly impregnable defenses. And just like a Dutch dam, one little leak (of blood) is all it takes for their whole defense to come down hard and let every enemy Mook land dozens more attacks. Before long they're overwhelmed and either captured, KO'd or killed.
Normally the defense-breaking attack was already lethal and everything else was just icing on the cake. Sometimes it's a lucky hit that trips them up. Usually they still manage to kill a few dozen more enemies before being felled by injuries. This can be caused by enemies (either intentionally or through luck) exploiting the character's Achilles' Heel (whether Attack Its Weak Point, Kryptonite Factor or other things).
A couple of subversions are to have the character survive the onslaught and show up some time later, have the lucky hit cause a Minor Injury Overreaction, or become akin to a wrecking ball pin-cushion that's more destructive for having been put so close to death (without actually dying). An aversion is to merely have them take grazing damage throughout, or have lethal attacks kill instantly or post battle.
A side-wide version of this trope that replaces the lone hero with a Mook Maker structure is a common occurrence in Real-Time Strategy games, especially in Multiplayer Online Battle Arena types. Units can keep slaughtering each other for all eternity, but losing a single unit-producing structure almost guarantees that side's doom as their defenses are swamped (unless they manage to balance out the numbers).
Very much Truth in Television, as injuries can be debilitating or crippling even without inflicting significant damage otherwise. For example, some sword arts involve shallow slices to the arms or hands which might not sever the limb, but cutting the muscle or tendon will prevent it from properly flexing, thus reducing its functionality and making a more lethal follow-up much easier to land.
See also Keystone Army. See also/compare Dog Pile of Doom, where the mooks simply jump on the hero. Contrast Minor Injury Overreaction. Compare One-Hit-Point Wonder. Compare Injured Vulnerability, Lowered Monster Difficulty, Stun Lock and Not So Invincible After All.
- At the end of the Marvel Comics' Onslaught crisis the Hulk hits Onslaught so hard there's a tiny crack in his armor, which is more than anyone else could do. This is all the other heroes need to finally get through to defeat him.
- This is basically the whole deal with Gladiator, the leader of the Shi'Ar Imperial Guard in the Cosmic segment of the Marvel Universe. His powers are fueled by self-confidence, so he's effectively invulnerable until somebody somehow manages to land one he feels. From there it's all downhill, usually rapidly.
- The Matrix Reloaded. For most of the "Burly Brawl" fight between Neo and Agent Smith, Neo does quite well, not defeating the Smiths but holding his own. Near the end, as Neo is jumping from one Smith to the other, a Smith jumps out of nowhere and takes him down, allowing all of the other Smiths to dogpile on him. Because he's the One, he throws them off and escapes, but it's a near thing.
- When Boromir is fending off the Uruk-Hai in The Lord of the Rings he is killing them non-stop with nary a lucky hit, until their leader, Lurtz, manages to snipe him from afar.
- Mars Attacks! Near the end Byron Williams faces off against a horde of Martians in hand to hand combat so the others can escape. He repeatedly punches the Martians until one of them jumps on his back and prevents him from defending himself, whereupon the rest swarm over him and take him down.
- District 9. The Prawn Mini-Mecha appears to be Immune to Bullets until it gets hit with a BFG (specifically, a South African 30mm anti-tank rifle), and from that point onwards it gets more and more easily damaged until it gets shut down by a simple 9mm pistol. Wikus still gets his fair amount of mileage out of it, though.
- As the page quote bears out, the Jedi can easily deflect blaster bolts up to a certain point, which is what Palpatine uses to wipe them out with Order 66 in Revenge of the Sith; the Jedi not taken completely by surprise in the first place are unable to ward off such concentrated blaster fire and are quickly felled once a single bolt gets through their defense.
- In Rurouni Kenshin: The Legend Ends, Kenshin and Sojiro's rematch has them fairly equal at first until Kenshin manages to get in a hit on Sojiro's legs, causing him to slow. From then on Kenshin manages to land more and still more hits on Sojiro, until he can use his Finishing Move.
- In Godzilla: Final Wars, the Controller tosses Ozaki around like a ragdoll until Ozaki manages to stun him with a punch to the throat. Then Ozaki turns the tables and beats him down.
- Discussed in Barbara Hambly's Star Wars Expanded Universe novel Children of the Jedi. As Jedi-turned-computer entity Callista notes to Luke, a Jedi may be able to fend off blasterfire for a while, but once one mook gets lucky, more mooks will get lucky. That's how Callista died the first time around.
- The Ciaphas Cain novel "The Last Ditch" has a big Tyranid monster able to shrug off lasgun and bolt pistol fire until an air-to-surface missile breaches its carapace, allowing the squad to aim for the breach and bring it down.
- The second time Cain fights a Chaos Marine in The Traitor's Hand, he takes advantage of prior battle damage to the Marine's armor, and shoves his chainsword through the breach to incapacitate the Marine.
- In The War of the Ancients, Sargeras is pretty much unstoppable until Broxigar scratches him with his enchanted axe. That very slight injury was all the heroes needed to stop Sargeras.
- In The Ballad of the White Horse, Eldred is an unstoppable force of destruction - until his sword breaks.
"Then from the yelling Northmen driven splintering on him ran.""Full seven spears and the seventh was never made by man."
- Harry Potter: When he first tries out for Quidditch as Keeper, Ron suffers from massive lack of self-confidence that causes him to get worse with every goal he lets through. The day of the final match, he lets in a few... and suddenly has a bolt of inspiration that causes him to block every goal and sees his team win the game.
- Pact briefly features a pair of Creepy Twins, a male and female pair of Others who mimic one another's movements and fight as one. The chink in their armor is their need to manually Sychronize—that is to say, when one of them is injured, their supernatural teamwork stops working until the other inflicts the same injury upon themselves. Blake capitalizes on this opening, leading to a cycle of injury and self-injury that ends with one taking a lethal wound and the other committing suicide in the same way.
- In GURPS, this is what some players refer to as the "death spiral". A Major Wound (equivalent to half or more of a character's maximum HP) can send a character tumbling to the ground and/or stun them. On the ground, defenses are compromised. Stunned, defenses are compromised even further. Being both stunned and prone cripples defenses to the point where you had better hope your opponent whiffs on their next attack or you roll a Critical Success on your own defense roll. Ergo, barring extraordinary toughness or good armor, it is best not to be hit in the first place.
- Since then, "death spiral" has become a general word for any mechanic that puts a wounded character at a disadvantage, since it tends to lead to this trope: even fairly minor penalties can easily tip the scales, which of course gets the character more hurt, which imposes further penalties, which gets them hit more, digging them ever-deeper in the hole with less and less chance of turnaround. It's generally agreed as being realistic, but not cinematic, and a dangerous mechanic to include unless its implications are well-considered.
- This is an aspect of the FATE system, including The Dresden Files, where once a character is hit hard enough to take a Consequence, that can subsequently be used to gain a bonus on attacks against them, leading to more, harder hits and a quick end to the fight.
- Can easily happen in Diablo III to characters with an over-reliance on items providing Life Per Hit or Life Per Kill. During the normal course of combat, you're constantly healing more quickly than the enemy can damage you, and your health barely ever dips at all. Then an elite gets in a lucky shot with a freeze blast, and you're dead before you can recover.
- This can happen to an unwary survivor in Left 4 Dead and Left 4 Dead 2. Speed and accuracy more than hitting power are your best friends, because your objective isn't to kill all the zombies but make it to the end of the level. A player or team can do great until one attack by a Common Infected slows them down, and suddenly dozens more can pile on damage before you know it. The same goes for Special Infected but even moreso, and this trope is at its most prominent in Expert Realism mode, where survivors are Glass Cannons.
- The same is also true of Killing Floor, as the generic Clot is little threat, but getting hit by one slows down the victim because Clots can perform grabs and mire the surivors in a sea of Zeds. A player that was otherwise handling themselves just fine is suddenly at the mercy of a decidedly merciless horde.
- The normal outcome of combat in Dwarf Fortress. Sometimes a lucky hit inflicts enough pain to incapacitate a combatant, sometimes losing a limb leaves the foe literally disarmed (especially useful for bandit and invader weaponmasters) and unable to parry attacks, or sometimes it's one of various injuries that slow the victim down.
- Likewise, in RimWorld, limbs can be damaged or destroyed, and pain cripples consciousness, leaving a colonist or enemy with less ability to flee or fight back once they get hit just once. Thankfully, if someone is incapacitated but not killed, most enemies will focus their attacks on other nearby targets instead of finishing them off. This can also be bad when pirates decide to kidnap your colonists, a wild hungry animal is trying to hunt your downed colonist and eat them alive, or they are on fire and you can't get close enough to put them out.
- In Kartia: The Word of Fate, earning experience does not improve your health. What it does is improve your attack and defense stats. With good armour and a strong character, it reaches a point where enemies keep having their attacks bounce off your party members for no damage. But whenever a human or Phantom is injured, its attack and defense attributes goes down. So previously invulnerable units may find themselves being hit by attacks they'd previously been immune to.
- In RWBY, Pyrrha Nikos is going toe-to-toe against (admittedly worn out) Cinder Falls even powered up with the Fall Maiden's abilities. Then she gets hit with an arrow to the heel. Considering who she is styled after it's clear at this point in the battle Cinder's victory is assured, and although Pyrrha still has ranged weapons to attack with she dies with an arrow to the chest soon after.