Double Down

You attempt to magically overclock your mind to perfect an action you are about to perform, adding an additional D10 or D20 die to your ability check, attack roll, or saving throw.

If the sum of your rolls exceeds 21 however, your mind gets overwhelmed by the psychic jolt. With smokes and sparks and a crisp bang sound out of your head, you automatically fail the roll and become Stunned until the start of your next turn.