If Primeval Spawn would enter the battlefield and it wasn't cast or no mana was spent to cast it, exile it instead.
Vigilance, trample, lifelink
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.
Near Mint - $700
Lightly Played - $500
Moderately Played - $500
Heavily Played - $400
Damaged - $400
Near Mint Spanish - $700
Lightly Played Spanish - $500
Moderately Played Spanish - $500
Heavily Played Spanish - $400
Damaged Spanish - $400