Well, BLU does get Voracious Trunk, so Aura Steal in spell form does exist to some degree. The latter idea makes me think of Reverse, where in XII a cure spell would hurt you while damage would cure you. While a debuff of the same name shouldn't carry that effect, reversing the effect of personal buffs could be interesting. Just tricky deciding what it'd do for things like Stoneskin or Spectral Barrier.