Vlaakith, the Lich Queen

Eminence - whenever you cast a spell, if Vlaakith, the Lich Queen is on the battlefield or in the command zone, place
an arcane counter on Vlaakith. You may
cast a spell with mana value X or less
without paying its mana cost, where X is
the number of arcane counters on Vlaakith,
the Lich Queen. If you do, remove all
arcane counters from Vlaakith.