Sol Ring

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Eiganjo, Seat of the Empire

{T}: Add {W}.
Channel — {2}{W}, Discard this card: It deals 4 damage to target attacking or blocking creature. This ability costs {1} less to activate for each legendary creature you control.

Three Tree City

As Three Tree City enters, choose a creature type.
{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.

Kemba, Kha Regent

At the beginning of your upkeep, create a 2/2 white Cat creature token for each Equipment attached to Kemba.

Plains

Arcane Signet

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

Sculpting Steel

You may have this artifact enter as a copy of any artifact on the battlefield.