Timed Toxin

When you cast this spell, one creature becomes infested with a poison that lays dormant. At any point, you can choose to activate the poison as an action. As soon as this happens, the target must make a Constitution saving throw or take 4d6 Poison damage and become poisoned for 1 minute. They may make another Constitution save at the end of each of their turns to end the poisoned condition. If they succeed on the save, they take half damage and aren't poisoned.