Critical Strike

Critical strike is a passive ability that gives the chance to deal a bonus percentage damage on a succesful attack of the wielding unit.

Mechanics
Critical strike is defined by two values: the critical chance and the critical damage multiplier.

Critical damage is physical damage and reduced by various types of armor. The red number shown by critical strike is displayed before reductions (this is why illusions don't show very low red numbers). Critical strike does not work against buildings. Because critical strike multiplies the attack damage of a unit, it is a scaling ability (unlike the damage of Monkey King Bar's mini-bash ability). All critical strikes that are granted by a Hero ability are subject to pseudo-random distribution. This special mechanic does not apply to critical strikes that are granted by Items or Neutral Creep abilities, however.

Interaction with other passive abilities

 * Critical strike: Multiple critical strike abilities do not independently stack, as they can not trigger on the same hit.
 * Lifesteal: Lifesteal is calculated after critical strikes, which means that it will increase the amount of life you steal.
 * Cleave: If critical strike is triggered, the damage dealt to all units will be multiplied.
 * Bash and mini-bash: Bashes and Critical Strikes can proc off of the same attack, but only the damage of ranged Bashes will be multiplied (with the exception of Monkey King Bar).
 * Illusions: Illusions can use the critical strike ability. (The red number above the just-crited illusion is showing damage before the reduction)
 * Shadow Blade: The 150 bonus damage when breaking invisibility can be multiplied by critical strike.

Pseudo-Critical Strike
The following abilities involve a critical strike mechanic, although they are not triggered as a chance on attack.