You can use Urborg, Tomb of Yawgmoth to make all lands, including itself, tap for black mana. This can help you generate more black mana efficiently in your deck strategy.
Yes, Urborg, Tomb of Yawgmoth can be tapped for black mana.
Urborg, Tomb of Yawgmoth gives all land the basic type 'Swamp' in addition to other types. It is a card's basic type that determines if it can be tapped for coloured mana, and since Urborg gives itself the basic type 'Swamp' too, it means it can be tapped for black mana.
When Urborg Tomb of Yawgmoth is in play all lands are swamps in addition to their normal land type(s.) This card is a rare non-basic land and works great in a deck built around Angry Mob and Nightmare. A great multi-purpose land combo is Urborg, Tomb of Yawgmoth coupled with Gemstone Mine. Gemstone Mine is sacced after 3 taps normally, but if you have Urborg-Tomb Yawgmoth out then Gemstone Mine can be tapped for black w/out removing a mining counter from it, so that combo comes out looking like a pumped up vivid swamp. Throw in some Reflecting Pools and you can tap off any color w/outout losing mining counters
The Blood Moon has a significant impact on Urborg, Tomb of Yawgmoth because it changes the land's ability to produce colored mana, making it produce only red mana. This can disrupt strategies that rely on different types of mana, making it a powerful card in the game Magic: The Gathering.