Swamp

Arcane Signet

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

Sol Ring

Baleful Strix

Flying, deathtouch
When Baleful Strix enters, draw a card.

Island

Stitcher's Supplier

When Stitcher's Supplier enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)

Underground Sea

Mirko, Obsessive Theorist

Flying, vigilance
Whenever you surveil, put a +1/+1 counter on Mirko, Obsessive Theorist.
At the beginning of your end step, you may return target creature card with power less than Mirko's from your graveyard to the battlefield with a finality counter on it. (If it would die, exile it instead.)