Freezing Shadow

3-level Evocation

A black streak of shadows flies out of your hands to a point you choose within range. Shadows erupts in a 15-foot-sphere, killing all heat in that area. Each creature in that area must make a Constitution saving throw. A target takes 7d6 cold damage on a failed save, or half as much damage on a successful one. Every non magical light in that sphere extinguishes and light created by a spell of 1st level or lower is destroyed. Small amounts of water in that area freeze solid and the ground is covered in slippery ice causing it to become difficult terrain 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 1d6 for each slot level above 3rd.