The Arena of Champions

{t}: Add one mana of any color. Spend this
mana only to cast legendary spells.
{x},{t}, Sacrifice The Arena of Champions:
Search your library and/or graveyard for a
legendary card with converted mana cost X,
reveal it, and put it into your hand. If you
search your library this way, shuffle it.
"We shall let the arena decide who the champion is!"