When attacking, if you land a natural 20, and the total of your attack roll is high enough to hit the target's defense, it's a critical hit!
- Maximum Damage: Instead of rolling the power's damage, you deal max damage. For example, a power that deals 2d10 + 4 damage would deal 24 damage. Extra damage dice that were added to the attack (such as sneak attack and hunter's quarry) are also maximized.
- Extra Damage: Some effects add extra damage to a critical hit. This includes most enchantments for weapons and implements, high crit weapons, some feats (Devastating Critical), and other effects. You roll this extra damage on top of your power's maximized damage.
- Extra damage rolled on a critical is not maximized. Thus a magic weapon that adds 3d6 to a critical requires that you maximize the power's normal damage, then roll a d6 3 times and add that to the total.
- Some feats, class features and powers allow you to crit on numbers beside 20. For example, the Axe Mastery feat allows critical hits on a 19-20 with axes.
- A coup de grace that hits is automatically a critical hit.
- Some feats and other effects trigger off of a critical hit. For example, Surprise Knockdown.
- If you rolled a natural 20 but didn't beat the target's defenses, it is an automatic hit rather than a critical hit.