Swamp

Doom Blade

Sign in Blood

Target player draws two cards and loses 2 life.

Marshmist Titan

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Ruthless Ripper

Deathtouch
Morph—Reveal a black card in your hand. (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Ruthless Ripper is turned face up, target player loses 2 life.

Cast Down

Deathgaze Cockatrice

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Terror

Destroy target nonartifact, nonblack creature. It can't be regenerated.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Fleshbag Marauder

When Fleshbag Marauder enters, each player sacrifices a creature of their choice.

Doomed Dissenter

When Doomed Dissenter dies, create a 2/2 black Zombie creature token.

Cadaver Imp

Flying
When Cadaver Imp enters, you may return target creature card from your graveyard to your hand.