Cooki explosion

A giant cookie explodes on your enemy as you die for funni vengence

As your hit points turn to zero, you can use your reaction to cause a cookie explosion centered on the enemy that killed you, doing 5d10 + modifier damage and turning your opponent into a cookie for 2 rounds. (on a failed save) While your opponent is a cookie, they are unable to take actions or bonus actions or move. This is only able to be used if you're a cookie race. 

On a successful save, the opponent takes half as much damage and does not turn into a cookie.