Arcane Signet

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

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Miirym, Sentinel Wyrm

Flying, ward {2}
Whenever another nontoken Dragon you control enters, create a token that's a copy of it, except the token isn't legendary.

Exotic Orchard

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

The Ur-Dragon

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.
Flying
Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.