Legendary Shapeshifter

{t} Add one mana of each color that you can produce in your library.
{x} Legendary Shapeshifter becomes a legendary creature of your choice from outside
the game until your end step after your next end step. It gains all of the chosen card's abilities. It gains power and toughness equal to the chosen creatures power and toughness. This costs X mana, where X is the mana cost (excluding color) of the chosen legendary creature.