Cheapest priced copy (World Championship Decks 1998): $6.49 at Card Kingdom, near mint, their price list as of .
Hall of Gemstone 
World Enchantment · Rare · World Championship Decks 1998 · #bs221sb
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.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $6.49 to $15.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Mirage | 221 | Rare | $15.99 | — |
| World Championship Decks 1998 | bs221sb | Rare | $6.49 | — |
4 rulings from Wizards of the Coast
- 4 October 2004Will not affect lands that do not produce mana.
- 4 October 2004Although the color may be altered, any restrictions on the use of the mana are not removed.
- 1 October 2008This 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 August 2016Any colorless mana that's produced isn't affected.