When Bloodthirsty Adversary enters the battlefield, you may pay 2R any number of times. When you pay this cost one or more times, put that many +1 +1 counters on Bloodthirsty Adversary, then exile up to that many target instant and or sorcery cards with mana value 3 or less from your graveyard and copy them. You may cast any number of the copies without paying their mana costs.