Text (9th): {Tap}: Add to your mana pool one mana of any color that a land an opponent controls could produce.
The ability can be played if the opponent has no lands that produce mana, but the effect will not be able to generate any mana. [Barclay 2003/10/29]
The generated mana is of the color the land would produce if tapped for mana after applying any effects (such as Phantasmal Terrain or Reality Twist) and any replacement effects (such as Naked Singularity) when determining the type of mana the land can produce. [WotC Rules Team 1999/03/18]
It only produces one mana even if the land can produce more than one. [D'Angelo 1995/08/02]
Can generate any of the colors the land can produce, even if the land is one of the Homelands lands which has a cost in addition to tapping in order to generate that mana. [Duelist Magazine #9, Page 37]
Works even if the opponent's lands are tapped. It only checks what kinds of mana can be produced, not if the abilities that produce them are usable right now. [D'Angelo 1996/10/31]
Can generate colorless mana if the opponent has a land which does so. [Duelist Magazine #5, Page 10]
The generated mana has any restrictions that the land's mana would have had. For example, if they have a Mishra's Workshop you could generate one colorless mana only usable for casting artifacts. [Aahz 1995/08/01]
