Yeah, that theory fell apart :( So, the Mage wasn't healing himself, then I don't understand the point of quickly using the ultimate ability. And most importantly - what negative debuff was applied?
Or maybe he was infecting them. Throwing a stun on Rick doesn't seem that useful, and wasting the ultimate on scouting is pointless. The psychic attack of the Hag is an interesting thing, but it will only become clear the following night.
The only reason not to save the ultimate is that the roles of the killed players won't be guessed, and then you can end up in a void.