In my headcanon, Q squished Nagilum between his metaphorical fingers for being so impotent as to kill a life form on a whim without possessing the capability or forethought to restore them (for further amusement). Then he brought Ensign Haskell back who rotated out to a new assignment as Lieutenant.
Daystrom is about the normal 10 to 20% ... Shitty daystrom is probably 50% which is about the point where you start drooling but still consciously functional.
Risa is 100% and we're convulsing on the floor waving our hands around and someone duct taped a mouse to one hand and gave access to a keyboard on the other.