Once on each of your turns, when you deal damage with a Warmage cantrip, you can double the number of damage dice dealt by the spell, as if you scored a Critical Hit. If you use this feature to improve a spell that has already scored a Critical Hit, the cantrip deals triple the number of damage dice in total.
You can use this feature twice. You regain one of its expended uses when you finish a Short Rest, and you regain all expended uses when you finish a Long Rest. You gain an additional use when you reach Warmage level 11.