IDK. 45s cooldown Desperate Prayer sounds like unkillability while levelling, a big deal in early instances when tanks have issues holding AE threat. Plus later on it heals osmeone else, too.
But yeah, contests for worst. My personal favorite here is Felguard, they even said themselves before that they don't want to do that because then Demolocks lack all the experience how to use their various pets since there is no reason to.
Hrm, tricky. Either Thunderstorm or Pyroblast.
-- (The Death of Rats, Terry Pratchett, Soul Music)