Emberfrost's Rimed Fulmination Bolt

Holding a White Dragon scale in one hand and a Blue Dragon scale in the other arcane energy arcs between the two scales forming an ice ball pulsating with lightning energy, you release the sphere towards a creature in range. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 3d8 cold damage and 3d8 lightning damage on a failed save target is stunned for one round, or half as much damage on a successful one and isn't stunned.

The lightning spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.