Text (DK+errata): {Tap}, Exile a creature you control: Put a storage counter on ~this~. ; {Tap}: Add {X} to your mana pool, where X is the number of storage counters on ~this~. [Oracle 2009/07/08]
The counters do not go away when it is used. [bethmo 1994/08/15]
Can be tapped for zero mana if it has zero counters. [D'Angelo 1994/12/19]
It is considered "tapped for mana" for purposes of Mana Flare and Wild Growth even if it has zero counters on it. [WotC Rules Team 1994/12/15]
Extended tournaments (see Rule 913) have banned this card since 1999/10/01.
