Decompose

You reach out and touch the corpse of a creature.  Over the course of the next minute, the corpse begins to rapidly decompose, sprouting fungus and moss as it begins to degrade into compost and mulch.  An odd-colored flower or two may spring from the corpse in this time.  Applicable requirements for resurrection are unaffected by this decomposition.
You can target an undead with this spell, if you do, it takes 2d8 shadow damage.

The spell’s damage increases by two die when you reach 5th level (4d8), 11th level (6d8), and 17th level (8d8).