I've already found a bug in the demo, sorry. :P
I can use the LEMMISI run for free as the sorcerer in the swamp dungeon (I believe it's the second dungeon of the normal difficulty) and it doesn't reveal any blocks. I can just stand there and spam it, filling my health up, and it doesn't fill any monster's health up.
EDIT: I'm also manaburned. I don't know if that affects it or not.