Turn Demon is a missile spell with a timeout. If you cast it right at your feet, it does nothing. It also does not get a timeout. It also doesn't consume any mana. So you can just keep casting it indefinitely at your feet. This isn't particularly exploitable unless you have triggers that work "on cast", as those still fire. If you have strong things that trigger like that, it's quite potent, although I'm not sure if any strong cast triggers exist in vanilla dredmor. Perhaps "On Cast" should only work when mana is consumed?