Demonic Cold

Demonic Cold 4th level Evocation
Casting Time: 1 action
Range: Self (30-foot-radius sphere)
Target: Self (30-foot-radius sphere)
Components: V S
Duration: Concentration, Up to 1 minute
Element: Ice
Air gets cold like in ice age. A large grinning demonic face made of the snow particles forms in the sky. When a creature, except yourself, enters the spell's area for the first time on a turn or starts its turn there, it must make a Constitution saving throw. It takes 1d8 Ice damage on a failed save, or half as much damage on a successful one. Everything within the area is covered with frost, creeping up and encasing anything unfortunate enough to be within the area of effect. Each turn spent in the area gives a creature one level of Freezing.
The entire area affected by the spell counts as difficult terrain. Any creature moving within it for the first time on their turn must make a Dexterity saving throw or fall prone.
At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d8 for each slot above 4th.