Pyrotin, King of Fire

When Pyrotin enters the battlefield
exile the top five cards of your library where
X is the number of spells you have cast
this turn. You may cast instant and sorcery
spells from among them without paying its
mana cost.
Whenever you cast an instant or sorcery spell
for the first time each turn exile Pyrotin then
return Pyrotin to the battlefield tapped.