Eldrazi Oracle

At the beginning of each player's upkeep, that
player exiles the top card of their library. It perpetually gains "You may spend mana as
though it were mana of any color to cast this
spell."
Nonland cards exiled this way may be played by
any player for as long as they remain exiled. The
owner can cast it for {2} plus their cost and opponnents can cast it for {4} plus their cost.