Masaio, The Monarch Elder

Masaio enters the battlefield with a Butterfly
counter on it
Whenever you cast a spell with {x} in its mana
cost put a Butterfly counter on Masaio for each {x} in its cost
{t}: Add {g} for each Butterfly counter on Masiao.
Spend this mana to only cast spells with {x} in its
mana cost