Sol Ring

Arcane Signet

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

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Indestructible (Effects that say "destroy" don't destroy this artifact.)
{T}: Add one mana of any color.

You have no maximum hand size.
{T}: Add {C}.