Core rule
Critical hits
A critical hit rolls the attack’s damage dice twice. Flat damage bonuses are not doubled.
An unmodified attack die of 20 normally produces a critical hit. A final total of 20 after adding bonuses is different.
Some items lower the required die result, while certain conditions enable critical hits in other ways. These rules are separate from attack bonuses.
Normal hit1d8 + 3Critical hit2d8 + 3
This example has no extra damage effects.