Here is another installment of exTRAPaganza, our Thursday over-the-top trap series.
Slight rumbling can be heard from above. The occasional pebble falls from the ceiling. A rock is wedged into large opening.
The rock can be dislodged with a hard Strength check. However, the rock is also supporting the ceiling. When moved, the river above crashes through. Anyone within 15′ of the rock takes heavy damage, with a hard Dexterity saving throw halving this damage.
The area quickly fills up with water, and all targets in the area start to drown unless measures are taken