Melphiris the Evoker

Whenever you cast a spell for it's Evoke cost, gain
an experience counter.
Permanent spells you cast have Evoke. The evoke
cost is it's mana cost reduced by the number of experience counters you have. This effect reduces
only the amount of generic mana you pay. (You
may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)