Why Are You Hitting Yourself?

You compel a creature you can see to attack themselves. The spell has no effect against undead, constructs, creatures with less than a 4 intelligence score, and creatures who are immune to being charmed.

The target must succeed on a Intelligence saving throw or make an attack against itself with the weapon in their dominant hand (if their dominant hand is empty, they make an unarmed attack). They must roll an attack roll with that weapon against their own AC. Roll 2d10. This attack cannot deal more than that amount of damage. Any additional on-hit effects that come from the creature or their weapon still apply. 

Using a Higher-Level Spell Slot. The maxiumum attack damage increases by 1d10 for each spell slot level above 1.