Command Tower

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

Arcane Signet

Exotic Orchard

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

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.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Path of Ancestry

Path of Ancestry enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Portal to Phyrexia

When Portal to Phyrexia enters, each opponent sacrifices three creatures of their choice.
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control. It's a Phyrexian in addition to its other types.

Swamp

Mountain

Forest

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Island

Plains

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Kodama's Reach

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.