PF: Critical Momentum

...

Critical Momentum

On your turn, an amount of times equal to your proficiency bonus + 1, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with a weapon; you gain a single Additional Attack, as per the Common Feature. If you're within 10 ft of an ally who rolls a skill check, and fails a Success or Critical Success by at least 2, you may use your reaction to help them for free, turning the check into a Success or Critical Success. Instances of this from multiple creatures do not stack.

Prerequisites Character level 6th