Pisces, The Third Elder

Pisces, The Third Elder can't be blocked.
Whenever Pisces, The Third Elder enters the battlefield or attacks, look at the top four cards of your library. You may put a instant or sorcery card from among them with converted mana cost
5 or greater into your hand or you may cast an instant or sorcery card from among them that has converted mana cost 4 or less. Put the rest of the cards at the bottom of your library in any order.