Animate devil chains

The chains on the maul come to life at your command. Choose a target within range and make a +2 grapple check against it. On a succesful grapple you must succeed on a DC 15 wisdom saving trrow or enter a state of trance. during this trans, the chains will awaken, sprout sharp hooks and edges and start killing the grappled creature slowely.(2d6 at the start of its turn) if you succeed the saving throw, you may choose to awaken the chains regardless but you will maintain you freedom of movement and the chains will not impede you from using the maul in combat.