Arcane Signet

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

Swamp

Cascading Cataracts

Indestructible
{T}: Add {C}.
{5}, {T}: Add five mana in any combination of colors.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Plains

Mountain

Island

Command Tower

Forest

Urborg, Tomb of Yawgmoth

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

Omnath, Locus of All

If you would lose unspent mana, that mana becomes black instead.
At the beginning of your first main phase, look at the top card of your library. You may reveal that card if it has three or more colored mana symbols in its mana cost. If you do, add three mana in any combination of its colors and put it into your hand. If you don't reveal it, put it into your hand.

Yavimaya, Cradle of Growth

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

Leyline of the Guildpact

If this card is in your opening hand, you may begin the game with it on the battlefield.
Each nonland permanent you control is all colors.
Lands you control are every basic land type in addition to their other types.