When you roll a natural result of 20 on a 20-sided die (D20) during a combat action, it is a critical success.
You deal additional damage or effects equal to 50% (rounded up) of the initial damage or effects.
Example :
If you were to deal 10 points of damage, a critical success would add an additional 5 points of damage.
Additionally, you can choose a tactical advantage, such as disarming the opponent, pushing them back, or disorienting them. The GM and player should work together to decide on the specific benefit.