Deep Freeze

You send a blast of deep cold at a creature, dealing 4d8 cold damage to it and encasing it in ice. 
An encased creature is grappeld and takes an extra 2d8 cold damage at the start of its turn every round it remains encased.
If the target of this spell makes a successful Dexterity saving throw, it takes half damage and none of the extra damage and is not encased in ice, but the ice that clings to its body reduces its speed by 15 ft (to a minimum speed of 5 ft) until it takes an action to remove the ice.

A grappled target can take an action to make a Strength check against your spell save DC, breaking free of the ice on a success. Alternatively, another creature within 5 feet of the target can make a Strength check on its turn, freeing the creature on a success. The ice can also be attacked. It has AC 12, 40 hit points, and vulnerability to fire damage. Hitting the ice deals half damage to the encased creature.

At Higher Levels When you cast this spell using a spell slot of 5th or higher, you can target one additional creature for each slot level above 4th.