Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Morbid Plunder

Return up to two target creature cards from your graveyard to your hand.

Nested Ghoul

Whenever a source deals damage to this creature, create a 2/2 black Phyrexian Zombie creature token.

Poison Counter

Phyresis

Enchant creature
Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Divine Offering

Destroy target artifact. You gain life equal to its mana value.

Phyrexian Crusader

First strike, protection from red and from white
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Phyrexian Rager

When this creature enters, you draw a card and you lose 1 life.

Phyrexian Vatmother

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
At the beginning of your upkeep, you get a poison counter.

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Scourge Servant

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Septic Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever this creature attacks, if defending player is poisoned, it gets +1/+1 until end of turn.

Spread the Sickness

Destroy target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Blisterstick Shaman

When this creature enters, it deals 1 damage to any target.

Burn the Impure

Burn the Impure deals 3 damage to target creature. If that creature has infect, Burn the Impure deals 3 damage to that creature's controller.

Frantic Salvage

Put any number of target artifact cards from your graveyard on top of your library.
Draw a card.

Mirrodin Besieged