Arms of the Abyss

The caster chooses a point within range, and 2d8 black tentacles burst out of the ground in a 20 foot radius centered around the point. The tentacles range in size from 10-25 feet long, and the ground is considered rough terrain for the spell's duration. Any creatures moving through the spell's area expend 5 feet for every one foot they move. All creatures in the radius when the spell begins must make a DC dexterity 18 saving throw, or take 2d10 bludgeoning damage for every tentacle that spawns, and half as much on a success. When a creature begins their turn in the mass of tentacles, or when entering the tentacles for the first time during a turn, they must make the same saving throw.