Acid Swarm

An acidic green swarm of magical insects surrounds you or an ally you touch.
They swirl around the target in a cube 10 feet on each side for the duration.

A creature takes 1D6 acid damage when it enters the spell’s area for the first time on a turn or starts, or ends its turn there. 

As a Bonus Action the target can give the swarm to another ally or command the swarm to haunt an enemy creature.
If an enemy creature is targeted, the swarm deals 2D6 on each of it's turns untill the spell ends.
It will however still hurt anyone in a 10-foot radius around the creature. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for each slot level above 4th.