Antigone's Freezing Orb

You create an orb of cold energy and hurl it at one creature within range. Make a ranged spell attack against the target. On a hit, the target takes 2d8 bludgeoning damage. Hit or miss, the orb then explodes. The target and each creature within 10 feet of it must make a Dexterity saving throw.  On a failed save, the target takes 6d6 cold damage, and its speed is reduced by 10 feet until the start of your next turn. On a successful save, the target takes half as much damage and suffers none of the spell’s other effects. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the cold damage increases by 1d6 for each slot level above 3rd.