Endotherm

As you inhale, you drain the heat from the air and the creatures around you in a 20-foot radius sphere. Each creature must make a Dc 15 Constitution saving throw. On a failure, the affected creatures must 5d6 cold damage and has it speed reduced by 10 until the start of its next turn. On success, the creature takes half damage and is not slowed. Until the end of your next turn, your speed is increased by 10 for each small or large creature that failed the throw. 

At Higher Levels. when you cast this spell at any level above 4th, the damage is increased by 1d6 for each slot level above 3rd.