Critical hit (Borderlands)

Description
In addition to the increased amount of damage inflicted, the word "CRITICAL" is displayed in floating red text to the player scoring the critical hit. Damage caused by critical hits can be increased by using a weapon with +X% critical damage modifier, as seen on sniper rifles and certain other weapons. Other weapons such as revolvers and Death assault shotguns deliver a bonus to critical hit damage, even if no bonus is listed on the weapon's card. Lilith and Mordecai also come with class skills that increase critical hit damage, and they both have class mods that also increase sniper rifle critical hit damage, and team critical damage.

Melee attacks can also cause critical hits. Mordecai's critical hits yield the highest damage of any class in Borderlands, due to his many critical hit skills and modifiers. With his Lethal Strike melee skill and a bladed weapon, a strike to a critical area can easily deal over fourteen thousand damage to a same-level enemy.

With many enemies, taking a critical hit can stun them, causing them to perform a flinch animation. By targeting a critical zone with rapid-fire automatic weapons (SMG, Machine Gun, etc.) or rapid Berserk punches, players can effectively "crit-lock" enemies, rendering them virtually unable to attack until they stop getting hit in their critical area. This strategy is more easily used on enemies who don't have too drastic a flinching animation when their critical area is shot, which may move the critical area out of a player's crosshair. However on these enemies slower weapons like sniper rifles (or carefully burst firing an auto weapon) can crit-lock by simply waiting until the enemy's flinching motion is finished, and shooting the same place again.

Critical hit areas on enemies

 * The Destroyer: Eyes, mouth, and the glowing purple spots on each of its spine-launching tentacles. Each tentacle will be destroyed after it has sustained enough damage and this will prevent that tentacle from launching spines, but tentacles will regrow after a while. A Bloodwing will always attack these critical targets.
 * Guardian: Head.
 * Human: Head.
 * Larva Crab Worm: Purple glowing eye in the middle of the head. Larva Crab Worms take extremely high damage from critical hits. Note that if a weapon with splash damage is used on these, any frontal hit (even on claws) may yield a critical hit.
 * Mulciber Mk2: Head of the human gunner.
 * Rakk: No critical hit areas. Rakk are generally fragile and cannot take much damage.
 * Rakk Hive: Mouth and eyes. Each eye will be destroyed after it has sustained enough damage, but further shots on a destroyed eye socket will still yield critical hits.
 * Scythid: No critical hit areas.
 * Skag: Inside of mouth. A critical hit is more likely with its mouth open, but closed-mouth critical shots are possible, too, especially on Skagzilla due to the size of its mouth. Skag are vulnerable to attacks against the closed mouth, too, though those will not yield criticals.
 * Spiderant: Abdomen (the rear part of the body behind the armored head). This critical hit spot can be easily accessed by shooting the head enough to daze the spiderant causing it to confusedly turn aside; explosive attacks to the head are quicker to cause dazing. Stray shots from the front (presumably passing over the top of the head and hitting the abdomen) can cause critical damage as well.
 * Turret: Fuel tank at the rear. The fuel tank can be hit from the front using an accurate weapon, as the wide tank slightly protrudes to the left and right when viewed from the front.

The Zombie Island of Dr. Ned

 * Undead Dr. Ned: Head.
 * Wereskag: Mouth and head. Since the wereskag is a combination of the skag and a human, the mouth covers the head.
 * Zombie: Head. Zombies take extremely high damage from critical hits.

The Secret Armory of General Knoxx

 * Craw Worm: Purple glowing eye in the middle of the head.
 * Crawmerax the Invincible: Giant purple glowing spots on his claws, his back, and his eye. Each critical area will be destroyed after being dealt sufficient damage, and will not regenerate. He will die after all critical areas are destroyed. The only way to defeat Crawmerax is to use critical hits. Hits to any other parts will inflict no damage, regardless of the weapon used.
 * Devastators and General Knoxx: Head of the human pilot.
 * Drifter: Glowing spots on the ventral surface of the body, resembling eyes. These will rupture violently and gush a stream of ichor when burst, and cause the drifter to stumble. There is also a larger glowing area on its back.

Claptrap's New Robot Revolution

 * Claptraps: The optic mounted in front.

Mechanics
The general formula for critical damage is: CriticalDamage = BaseDamage &times; (1 + EnemyZoneBonus + WeaponCriticalBonus) Where:
 * BaseDamage: This the damage inflicted on an un-armored opponent.
 * EnemyZoneBonus: Is a per-enemy/spot specific bonus, related basically to "how critical" that part is.
 * WeaponCriticalBonus: This is the weapon card bonus (which may be hidden).

Example: a Revolver (+100% Critical), striking a bandit in the head (+150% Critical) will lead to a blow of a total of 350% Base Damage.

What is most interesting about this formula is that the two bonuses stack additively. This means that:
 * striking an opponent that has a high EnemyZoneBonus with a weapon that has a high WeaponCriticalBonus will not deal that much more damage.
 * Conversely, weapons with high CriticalBonuses will really show their full worth on opponents with low EnemyZoneBonuses.

WeaponCriticalBonus
This is the bonus as stated on most weapon cards.

The overall weapon critical damage breakdown is:
 * Repeater Pistols, Shotguns, SMGs, Combat Rifles: +0%
 * Shotguns with the Death title: +15% (unlisted)
 * Combat Rifles with the Intense accessory, Tediore Avenger: +50%
 * Tediore Avenger with the Intense accessory: +100%
 * Revolvers: +100% (unlisted)
 * Jakobs Unforgiven : +200%
 * Sniper Rifles: +180–200%
 * Sniper Rifles with the Gamble title: +250%
 * Jakobs Bessie: +500%

Melee
The critical bonus of Melee Strikes is that of whatever the weapon the player's hand is.

The Melee Bonus of Bladed/Spiked weapons (with the exception of Spiked assault shotguns) is applied multiplicativelly to the BaseDamage of the weapon. This Melee Bonus is hence the same regardless of whether or not the strike is critical.

EnemyZoneBonus
Below is a table containing the Bonuses for most enemies. Enemies that have not actually tested are not present in the table. Clap-Trapped enemies have the same bonuses as original enemy, unless noted otherwise.

Keep in mind that this bonus adds with the weapon's bonus (NOT multiply):
 * Sniper Rifles (and Revolvers) will be most efficient against enemies with low multipliers (Bandits, Spiderants, Crawmerax, Claptraps).
 * Conversely, enemies with high multipliers will take devastating damage from all weapon, so raw DPS is to be privileged over Critical Damage Bonuses (Larva Crab Worms).
 * Enemies with "intermediate bonuses" will still take high damage from Sniper Rifles (and Revolvers), but plain ordinance will also be quite effective (Skags, Crimson Lance, Rakk Hive, Devastators)

Notes:
 * Skags, Drifters and Crawmerax would seem to have a built in "Critical Overkill" protection, preventing any critical strike from damaging them more than their total health capacity.
 * The Crimson Lance, while taking a huge critical damage bonus, are also armored, reducing said damage by about 75%.
 * Consequently, critical hits are not that much more damaging than hits to the (larger) unarmored groin area.
 * Because of the already large critical damage bonus they receive, critical shots received from sniper rifles will not be much more devastating than shots from, say, a Combat Rifle.
 * Drifters' critical spots would appear to be 1 hit kills.

Proficiency, Bonus Damage, Bonus Bullet Damage
Any effect that gives a bonus to a character's damage, be they from proficiency, skill, or mod, are considered to increase the "BaseDamage" of the character, and as such have a direct geometric effect on the resulting critical damage.

Deadly
Mordecai's Deadly skill is an additive bonus. It adds a fixed amount of BaseDamage to the resulting critical hit. It should simply be inserted into the formula to obtain: BaseDamage &times; (1 + EnemyZoneBonus + WeaponCriticalBonus + DeadlyBonus)

Sniper & Ranger Class Mods
Mordecai's Class Mods, Sniper and Ranger, have the same mechanic: They increase the current weapon's critical damage in a multiplicative fashion, and not an additive fashion. This means the mods are useless with most Repeaters or SMGs, but absolutely shine with Sniper Rifles.

For example, given a Ranger class mod that gives "+50% critical hit damage":
 * +0% critical hit Repeater Pistol => +0% critical hit Pistol
 * +100% critical hit Revolver => +150% critical hit Revolver
 * +180% critical hit Sniper Rifle => +270% critical hit Sniper Rifle
 * +250% critical hit Sniper Rifle => +375% critical hit Sniper Rifle

Basically, the higher the weapon's critical hit damage, the higher the bonus. The formula can be re-written as: BaseDamage &times; (1 + EnemyZoneBonus + WeaponCriticalBonus &times; (1 + ModBonus) ).

Sniper, of course, will only effect Sniper Rifles.

Please note that the Jakobs deviates from this formula. Please see for more information.