Polymorph [Ninth Edition] HER007-P If it has mana value

If it has mana value less than the sacrificed permanent's mana value

or planeswalker spell from your graveyard with mana value less than or equal to that spell's mana value without paying its mana cost

To the uninitiated

For wisdom's sake

you discard a card

Polymorph [Ninth Edition] HER007-P If it has mana valueSet: Ninth Edition Type: Sorcery Rarity: Rare Cost: {3}{U} Destroy target creature. It can't be regenerated. Its controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into their library.