Dolomar's Agonizing Anthill

You summon a towering anthill at a point within range. Thousands of fire ants spill out of the hill and cover the floor in a 20-foot radius.

While in contact with the ground in this area in any way (directly or indirectly), a creature's speed is halved, and when the creature enters the area for the first time on a turn or starts its turn there, it must make a Dexterity saving throw. On a failed save, the creature takes 3d6 piercing damage and 3d6 acid damage. On a successful save, the creature takes half as much damage.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the radius increases by 10 feet for each spell slot above 3rd.