Darkbranding

You target one creature within range and attempt to bind it to your rules. The creature must succeed on a Constitution saving throw or be branded. The brand can be removed with a Remove Curse spell, or when you drop concentration with an action. For the duration the creature takes 1d6 fire or necrotic damage (your choice), ignoring vulnerability, every time it is taking actions, bonus actions, or reactions other than to dodge, dash, disengage, hide, talk, escape a grapple, or make a saving throw. At the start of the creature's turn it can attempt to ignore the effects of the brand by making another Constitution saving throw, on a success its actions aren't limited by the spell, on a fail it takes an additional 1d6 fire or necrotic damage based on your choice.

You may alter the nature of the trigger, but it may not be any stronger than the mentioned example.

When casting this spell using a 4th-level spell or higher, you increase the damage by 1d6 for each two slot levels above 2nd.