Term: Critical Success

Rolling 10 above a DC or AC, or rolling a natural 20 on a 1d20 , is considered a Critical Success.

Some effects within actions, abilities, and features have rules for when a creature Critically Succeeds a roll, usually increasing the severity of the effect and/or adding on a new dimension to such. Some, much like the combat effect below.

When it comes to Attacks of all varieties, when they Critically Succed, also known as a Critical Strike, Critical Hit, or just a 'Crit', the damage of the hit is increased by at least twice (more depending on the weapon) per increment, making the critical damage modifier additive. As an example, if a creature rolls +20 on over another creature's AC with a x3 weapon, that creature is dealt x6 damage. This increases to x9 with a +30, so on and so forth.