Star Compass

This artifact enters tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Arcane Signet

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

Leaden Myr

Fellwar Stone

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

Lazav, Dimir Mastermind

Hexproof
Whenever a creature card is put into an opponent's graveyard from anywhere, you may have Lazav become a copy of that card, except its name is Lazav, Dimir Mastermind, it's legendary in addition to its other types, and it has hexproof and this ability.

Silver Myr

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Sky Diamond

This artifact enters tapped.
{T}: Add {U}.

Commander's Sphere

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