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." Nothing else changes about those lands, including their names, other subtypes, other abilities, and whether they're legendary, basic, or snow.Urborg, Tomb of Yawgmoth helps black decks get colored mana from lands chosen for their utility. While it is on the battlefield, every land becomes a Swamp in addition to its existing types, gaining the ability to tap for black mana without losing its other abilities.
Cabal Coffers is its best-known partner. Urborg lets Coffers count all of your lands as Swamps, including Coffers itself, which can greatly increase the black mana its activation produces. It also gives Coffers an ordinary black-mana option when activating its larger ability would not be worthwhile. The combination is especially useful in mono-black decks with expensive spells and repeatable mana sinks.
Crypt Ghast adds another layer by producing an extra black mana whenever you tap a Swamp for mana. With Urborg active, your utility lands qualify too. A fetch land such as Polluted Delta can also tap for black while remaining on the battlefield, letting you postpone sacrificing it until you want the search or a landfall trigger.
The effect is symmetrical: opponents’ lands become Swamps as well, potentially improving their access to black mana. Urborg does not turn lands into basic lands and does not make copies of itself in your library searchable with Polluted Delta, because its ability functions on the battlefield. It is a fixing and synergy land rather than acceleration by itself. Include it when the value of black mana from utility lands, Coffers, or Swamp-related effects outweighs the assistance it may give other players.
