Urborg, Tomb of Yawgmoth (U40)

Provider	Type	Normal	Foil	Etched	Date
tcgplayer	retail	—	$190.14	—	2026-09-27
manapool	retail	—	$208.16	—	2026-09-27
cardmarket	retail	—	$103.79	—	2026-09-27
cardkingdom	retail	—	$179.99	—	2026-09-27
cardkingdom	buylist	—	$110.00	—	2026-09-27
cardhoarder	retail	$4.51	—	—	2026-09-27

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2021-03-19: Urborg's ability causes each land on the battlefield to have the land type Swamp. Any land that's a Swamp has the ability "{T}: Add {B}." Nothing else changes about those lands, including their names, other subtypes, other abilities, and whether they're legendary, basic, or snow.
2021-03-19: If an effect such as that of Magus of the Moon causes Urborg to lose its abilities by setting it to a basic land type not in addition to its other types, it won't turn lands into Swamps, no matter in what order those effects started to apply.
2021-03-19: Urborg, Tomb of Yawgmoth isn't a Swamp while it's not on the battlefield.
2021-03-19: Land cards not on the battlefield aren't Swamps while Urborg is on the battlefield.