Squelching Leeches

Squelching Leeches's power and toughness are each equal to the number of Swamps you control.

Fetid Imp

Flying
{B}: Fetid Imp gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Mind Rot

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Swamp

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Murder

Unnatural Endurance

Devoid (This card has no color.)
Target creature gets +2/+0 until end of turn. Regenerate it.

Typhoid Rats

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

Phyrexian Rager

When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.

Vampire Nighthawk

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

Gravedigger

When Gravedigger enters the battlefield, you may return target creature card from your graveyard to your hand.

Westgate Regent

Flying
Ward—Discard a card. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)
Whenever Westgate Regent deals combat damage to a player, put that many +1/+1 counters on it.

Reave Soul

Destroy target creature with power 3 or less.

Underworld Connections

Enchant land
Enchanted land has "{T}, Pay 1 life: Draw a card."

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, 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.)