Cloak of Vermin

You conjure a writhing garment of living insects that protect you and harm your foes. While the spell is active, you gain a +1 bonus to AC. Whenever a creature within 5 feet of you hits you with a melee attack, the insects lash out, dealing 2d4 piercing damage to the attacker.
As a bonus action, you can command your cloak to leave your body, becoming a swarm of insects, and enter the space of an adjacent foe. The swarm attacks that foe until you use a bonus action to command it to return to you, the foe moves more than 5 feet away from you, the spell ends, or the swarm dies. You lose the protective benefit of the cloak when using it in this fashion.