DOOOOM

You lock eyes with a living creature, marking one of you for death. At the start of the turn, for the target and the caster, they must make a death saving throw. If either get three successes, the effect ends on them. If either get three failures they die and the effect ends on the other target. 

At higher levels: When you cast this spell using a spell slot of 4th level or higher, you can target one additional creature for each slot level above 3rd. For each additional creature targeted, the caster must make an additional saving throw at the start of their turn.