The Killing Stone combines occult contract law with card-battling in an isolated 17th century mansion

I wasn't sure it would work. When it falls, a Derelict Fortress damages every enemy in front of it, but I've only seen that happen when one dies. Right now, my opponent—a devil with a face like a shivering circle of little wings made of gold—has a bunch of weedy enemies in a row I'd love to drop a tower on.

The Stunted Spawn card in my hand replaces a creature with a goopy monster that has higher stats, but will playing it on my Derelict Fortress trigger that on-death effect? If a tower falls in a goo swamp, does it cause damage?