Command Tower

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

To dizzying heights it rises, the gleaming spire, its tip threatening to pierce the blinding canopy. There it will all begin anew. Between Dark and Light, the pure and the corrupt—the one true struggle.

Final Fantasy Commander

If you don't have a commander, Command Tower's ability produces no mana.

If you have two commanders, the ability adds one mana of any color in their combined color identities.

If your commander is a card that has no colors in its color identity, Command Tower's ability produces no mana. It doesn't produce {C}.