If Primeval Spawn would enter the battlefield and it wasn't cast or no mana was spent to cast it, exile it instead. Vigilance (Attacking doesn't cause this creature to tap.), trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.), lifelink (Damage dealt by the creature also causes its controller to gain that much life.) When Primeval Spawn leaves the battlefield, exile the top ten cards of your library. You may cast any number of spells with total mana value 10 or less from among them without paying their mana costs.