Ravenous Rats

When this creature enters, target opponent discards a card.

Dauthi Slayer

Shadow (This creature can block or be blocked by only creatures with shadow.)
This creature attacks each combat if able.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Typhoid Rats

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

Murder

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Swamp

Cuombajj Witches

{T}: This creature deals 1 damage to any target and 1 damage to any target of an opponent's choice.

Vampire Opportunist

{6}{B}: Each opponent loses 2 life and you gain 2 life.

Tendrils of Corruption

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Vampiric Link

Enchant creature
Whenever enchanted creature deals damage, you gain that much life.

Liliana's Specter

Flying
When this creature enters, each opponent discards a card.

Ill-Gotten Inheritance

At the beginning of your upkeep, this enchantment deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice this enchantment: It deals 4 damage to target opponent and you gain 4 life.

Fume Spitter

Sacrifice this creature: Put a -1/-1 counter on target creature.

Order of the Ebon Hand

Protection from white
{B}: This creature gains first strike until end of turn.
{B}{B}: This creature gets +1/+0 until end of turn.

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Basilica Screecher

Flying
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Sign in Blood

Target player draws two cards and loses 2 life.

Dark Ritual

Crypt Rats

{X}: This creature deals X damage to each creature and each player. Spend only black mana on X.

Gray Merchant of Asphodel

When this creature 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.)

Chittering Rats

When this creature enters, target opponent puts a card from their hand on top of their library.

Onyx Goblet

Spark Harvest

As an additional cost to cast this spell, sacrifice a creature or pay {3}{B}.
Destroy target creature or planeswalker.