Decaying Blast

A sickly green blast of necrotic energy shoots off towards a creature of your choice within range. Make a ranged spell attack against the target. On a hit, the target takes 4d8 necrotic damage, and must make a constitution saving throw against your spell save DC. Should they fail the saving throw they will have the poisoned condition until the end of your next turn. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.