Commander's Sphere

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

Fellwar Stone

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

Biophagus

Genomic Enhancement — {T}: Add one mana of any color. If this mana is spent to cast a creature spell, that creature enters with an additional +1/+1 counter on it.

Byode, Inverse Sun

+2: Mill three cards, then return any number of cards from different Universes milled this way from your graveyard to your hand.
-X: Choose a Universe you haven't chosen this way this game. You may cast a spell from that Universe with mana value X or less from your hand without paying its mana cost.
Byode, Inverse Sun can be your commander.
Your deck can include Universes Beyond cards of any color identity.

Reclusive Taxidermist

Reclusive Taxidermist gets +3/+2 as long as there are four or more creature cards in your graveyard.
{T}: Add one mana of any color.

Arcane Signet

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

Inherited Envelope

When Inherited Envelope enters, the Ring tempts you.
{T}: Add one mana of any color.