Gandalf the White

Gandalf the White may only be played if Gandalf
the Grey is already in play. If so, Gandalf the
Grey gets exiled.
{x}: Tap target creature with converted mana
costs X or change the target of target spell with
converted mana costs X.
{t}{x}: Search your library for a card with
converted mana costs X and bring it into play.
Shuffle your library afterwards.
"All we have to decide is what to do with the
time that is given us."