Amusing idea for a 3.5(maybe 5e) spell:
Rationed Carnage - When you cast this spell, target gains a pool of dice equal to twice your caster level. As a free action, the target may apply up to (spell level) dice from the pool to an attack, before the target makes the attack roll. The target deals that many additional d6s of damage. Dice not applied to an attack within the duration of this spell disappear. Lasts for minutes/level.