Text (4th+errata): At the beginning of your upkeep, sacrifice ~this~ unless you pay {W}{W}. ; All Mountains are Plains. [Oracle 2008/01/01]
The mountains becomes plains in all ways. They even produce white mana. [D'Angelo 1998/06/01]
Will not add or remove Snow-Covered nature from a land. [Duelist Magazine #6, Page 132]
The Conversion effect is a continuous effect. There is no chance to tap a just-played mountain for red mana before it becomes a plains. [D'Angelo 1996/12/10]
Extended tournaments (see Rule 913) have banned this card since 1999/10/01.
