Covenant

You and a willing creature that can see and hear you in range form a magic agreement. The agreement can be one-sided, an equal exchange, or anything between. Until the agreement's completed, both parties are marked with a symbol of your choice. Either party knows if the other fulfils their side of the agreement, and when both sides of the agreement are fulfilled, the spell ends.
The spell ends early if cast again or if a creature willingly breaches its side of the agreement. If a creature ends the spell or has another creature end the spell before it fulfils its side of the agreement, or if it willingly breaches its side of the agreement, a demonic mark brands its flesh with a permanent scar until healed by magic.