Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Prismatic Vista

{T}, Pay 1 life, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Cavern of Souls

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.