Vengeance

When you cast this spell, you return to health at 1 hit point. For the spells duration, the creature that took you to 0 hit points cannot deal damage to you, you have advantage on all attacks against that creature, and the creature has disadvantage on any saving throws you force it to make, you can use a bonus action on each of your turns to make an additional attack, cannot deal damage to any other creature, and fall back to 0 hit points after the spell ends.