This is awesome! I just tried this out - the mental die rolling method is genius.
I was in an earthern cave. I don't remember how I got there. There was an exit to my north and one far above me, but the north exit was blocked by rubble. I clear a bit of it only to notice a green gas seeping out from the room. I rush in, and find it's emanating from a broken tank. While trying to find something to cover the hole, a large porcupine-like creature wiggles out, with its long ant-eater mouth spewing the gas.
Definitely continuing this tonight as I fall asleep! Alfred Valley knocks it out of the park again.