Decompose

You gain a number of Temporary Hit Points equal to 1d8 plus your spellcasting ability modifier. Also, the first time you hit with an attack on your next turn, the target takes an extra 1d8 necrotic damage, and the spell ends.

The corpse of the enemy that died immediately decays as if 7 days had passed, shortening the time limit on raising the target from the dead.

Using a Higher-Level Spell Slot. Both the Temporary Hit Points and the extra damage increase by 1d8 for each spell slot level above 1.