Arcane Signet

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

Rakdos Signet

Fellwar Stone

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

Don Andres, the Renegade

Each creature you control but don't own gets +2/+2, has menace and deathtouch, and is a Pirate in addition to its other types.
Whenever you cast a noncreature spell you don't own, create two tapped Treasure tokens.

Steam Vents

({T}: Add {U} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Watery Grave

({T}: Add {U} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Izzet Signet

Dimir Signet

Command Tower

Dauthi Voidwalker

Shadow (This creature can block or be blocked by only creatures with shadow.)
If a card would be put into an opponent's graveyard from anywhere, instead exile it with a void counter on it.
{T}, Sacrifice this creature: Choose an exiled card an opponent owns with a void counter on it. You may play it this turn without paying its mana cost.

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Counterspell

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. This artifact deals 1 damage to you.

Evelyn, the Covetous

Flash
Whenever Evelyn or another Vampire you control enters, exile the top card of each player's library with a collection counter on it.
Once each turn, you may play a card from exile with a collection counter on it if it was exiled by an ability you controlled, and you may spend mana as though it were mana of any color to cast it.

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.