Feed the Worms 2014

You draw forth the ebbing life force of a creature and use it to feed the worms. Upon casting this spell, you touch a creature that dropped to 0 hit points since your last turn. If it fails a Constitution saving throw, its body is completely consumed by worms in moments, leaving no remains. In its place is a swarm of worms (treat as a standard swarm of insects) that considers all other creatures except you as enemies. The swarm remains until it's killed.