Leyline Compass

Manashift {1} - (You may cast Leyline Compass for
its manashift cost. If you do, it becomes the color that
you used to cast it and loses all other colors.)
When Leyline Compass enters the battlefield, if
it's colorless, draw two cards then discard a card.
As long as Leyline Compass is white, all lands are
plains in addition to their other types. The same
is true for blue and island, black and swamp, red
and mountain, and green and forest.