Critical hit multiplier

The critical hit multiplier is the number by which the base damage is multiplied upon a confirmed critical hit. Not to be confused with critical threat - which refers to how likely you are to land a critical hit. It also affects various damage effects coming from specific weapon enhancements;
 * Bursting effects
 * Elemental Burst
 * Holy Burst, Unholy Burst
 * Good Burst, Evil Burst
 * Maiming

Ways to increase multiplier

 * Competence bonus to critical hit multiplier can come from various sources. Multiple effects granting competence bonus don't stack.
 * Bard's Swashbuckling enhancement modifies the threat / multiplier as follows
 * Dagger, Shortsword, Throwing Dagger: +1 Threat, +1 Multiplier
 * Light Mace, Light Hammer, Kama, Sickle, Dart, Shuriken, Throwing Axe, Throwing Hammer: +2 Threat, +1 Multiplier
 * Kukri, Rapier: +1 Multiplier
 * Handaxe: +2 Threat
 * Light Pick: +1 Threat
 * Paladin spell: Holy Sword: +1 to threat and multiplier for all weapons
 * Staff Specialization, available for Rogues and Monks, add +1 to threat and multiplier for quarterstaves
 * Knife Specialization, available for Assassins, adds +1 multiplier for daggers and kukris. Additionally, it adds +1 to threat for daggers.
 * Expert Builder, available for Mechanics, adds +1 multiplier for bows, crossbows, and thrown weapons; +2 for great crossbows.
 * Insight bonus
 * Lethality, available for Assassins, adds +1 multiplier for any one-handed weapon you are wielding (Two Weapon Fighters will get the bonus for both weapons provided they qualify).
 * Vanguard's 5th core ability increases the threat range and multiplier of your shield by 1.

Many active attacks, often coming from enhancements, feats, or epic destiny abilities, modify the critical threat and/or multiplier of a single attack. These effects usually stack with everything else.


 * Most (all?) of these effects do not increase the multiplier of thrown weapons.

Ways to increase multiplier on 19 and 20
Multiple ways exist how to increase critical multiplier on the rolls of 19 and 20. All of these fully stack.


 * Howl of the North - Warchanter enhancements T5: +1
 * Death Frenzy - Frenzied Berserker enhancements 5th core: +1
 * Focused Wrath - Frenzied Berserker enhancements T5: +1 / +2
 * Bond of Retribution - Occult Slayer enhancements T3: +1 when below 50% HP
 * Bond of Destruction T5 removes the health requirement
 * Monks in Master of Stone or Grandmaster of Stone stance: +1 for monk weapons and unarmed attacks
 * Devastating Critical - Legendary Dreadnought: +1
 * Headman's Chop - Legendary Dreadnought: +1 if you have an axe in main hand
 * Overwhelming Critical epic feat: +1