Corpse Crushed

You summon a nearby spirit of the dead to aid you. You choose a target that you can see within 60 feet of you, forcing them to make a Constitution saving throw against your spell save DC. On failure, the spirit attached itself to the target and the target's movement is halved.

They may repeat the saving throw at the beginning of each of their turns; upon each successive failure, they become grappled. then prone, then incapacitated. 

The spell ends either when you choose to end it, your concentration is broken, or the target succeeds on their Constitution saving throw.