Toxic Barrage

You hurl three bolts of toxins. You can hurl them at one target within range or at several. Make a ranged spell attack for each bolt. On a hit, the target takes 1d12 Poison damage and must succeed on a constitution save against your spell DC. If the target is hit by multiple bolts they must make the saving throw on each hit. On a failure the target is poisoned for 1 minute. The creature remakes the constitution saving throw at the end of each of its turns, on a success the poison condition ends. 

Using a Higher-Level Spell Slot. You create one additional bolt for each spell slot level above 3.