Tickling Tentacles 2.0

NOTE: I just changed the classes.

Squirming, slimy tentacles fill a 90-foot square on ground that you can see within range. For the duration, these tentacles turn the ground in the area into difficult terrain.

When a creature enters the affected area for the first time on a turn or starts its turn there, the creature must succeed on a Dexterity saving throw or take 3d8 poison damage. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage (both initial and later) increases by 2d8 for each slot level above 2nd.