Tsathogga chooses an area of swamp that it can see within 120 feet of it. The area can be no larger than a 30-foot cube. Creatures in the area must make a DC 24 Strength saving throw. On a failed saving throw, the target takes 21 (6d6) acid damage and is grappled (escape DC 24). On a successful saving throw, the target takes half damage and is not grappled. On the next initiative count 20, the target takes an additional 21 (6d6) acid damage if it is still grappled by this lair action.