City of Shadows

Land
{T}, Exile a creature you control: Put a storage counter on City of Shadows.

{T}: Add {X} to your mana pool, where X is the number of storage counters on City of Shadows.¹
Illus. Tom Wänerstrand

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: The counters do not go away when it is used.
• 10/1/2009: You can activate City of Shadows's second ability while it has no storage counters on it, though it won't add any mana to your mana pool in this case. You've still tapped it for mana, though, in case any abilities (such as the ability of a Fertile Ground enchanting it) care about that.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard, MTGO Classic
Printings (2/3)	The Dark (Rare (U1)) MTGO Masters Edition III (Rare)