Urborg, Tomb of Yawgmoth

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

{T}: Add {C}.
{T}: Add {W} or {B}. Activate only if you control a Swamp.

({T}: Add {W} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

This land enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.

Lifelink
Menace (This creature can't be blocked except by two or more creatures.)
Spells you cast that target a creature cost {2} less to cast.

This land enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {B}.