Mythoyf's power is equal to the number of card types among cards in all graveyards +1 and its toughness is equal to that number plus 1.
(3): Exile target card from a graveyard search your library for a card that doesn't share a card type with it, reveal it shuffle your library and put it ontop of it.
See Challenge # 085. Tarmogoyf
Woo. That's certainly a difficult one to convert into a mythic, especially since Tarmogoyf was printed at mythic in Modern Masters. The second ability is certainly interesting. Got too many sorceries in the graveyard but no instants? Find some!