Blood Freeze

You begin to draw the heat from up to 5 creatures that have blood in a 10-foot radius sphere. The creatures must make a constitution saving throw. On a failed save the creature takes 5d8 cold damage and its speed is reduced by 30 feet until the end of its next turn. On a success the creature takes half damage and its movement speed is reduced by 10 until the end of its next turn. As an action on subsequent turns you may target another or the same 10-foot radius sphere and repeat this effect.

When you cast this spell with a spell slot of 8 level or higher it deals an additional 1d8 damage per spell level above 7