Caustic Mire

Greater Invocation
4th Level Spell

You can create an area of acidic sludge on the ground. Any creature who steps into it is slowed by about a third, and each 5' they move deals 1d6 acid damage to them. If a creature stands still in it they still take 1d6 acid damage each round. The sludge lasts one round per level, and you can only create one area at any given time.