Not quite casual, not quite hardcore, but I'd say the challenge is okay. Couple of annoying no-win situations(undergeared group on demon wall? better have a mage LB or you all die horribly. used at the wrong time/by the wrong person? You're doomed and you no longer have a way to build up a second one to use. group quit.) but otherwise, it's pretty good. never quite feels like you completely trounced whatever you were dealing with, but at the same time it rarely feels like you never stood a chance.