Vilmari's Bloated Burst

You send necrotic energy coursing through three creatures that you can see within range. The targets must make a Constitution saving throw. They take 5d12 + 40 necrotic damage on a failed save, or half as much damage on a successful one. If a creature's hit points drops bellow zero they immediately swell to an impossible size before exploding, causing instant death.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, add 1d12 necrotic damage, and you may target one additional creature for each slot level above 4th.