Overseer of the Debt-Bound

Flying
Creatures target player controls becomes tapped
and cannot be untapped unless that player pays
{5} for your spells during your turns for the next
3 turns.
"You are not yet free of your debt. You are still bound
by the contract. If you think you can escape your servitude, I will be there to make sure you don't. Think
on this, next time you try something foolish."