Yke, Archmaster's Destroyer

Lose {x} life, {t}: Exile {x} cards from
the top of your library and replace
their cost with {u}{r}. Until the start of
your next turn you may play
instant and sorcery spells exiled this way.
At the start of your turn put all cards
exiled this way to your graveyard.
If Yke, Archmaster's Destroyer is your commander
spells (not lands) in your deck can be of any colour