At the beginning of each player's upkeep, that player chooses a color. Until end of turn, lands tapped for mana produce mana of the chosen color instead of any other color.
(04/10/2004)
Will not affect lands that do not produce mana.
(04/10/2004)
Although the color may be altered, any restrictions on the use of the mana are not removed.
(01/10/2008)
This has the supertype world. When a world permanent enters, any world permanents that were already on the battlefield are put into their owners' graveyards. This is a state-based action called the "world rule." The new world permanent stays on the battlefield. If two world permanents enter at the same time, they're both put into their owners' graveyards.
(23/08/2016)
Any colorless mana that's produced isn't affected.
