Corpse Cur

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When this creature enters, you may return target creature card with infect from your graveyard to your hand.

Virulent Silencer

Whenever a nontoken artifact creature you control deals combat damage to a player, that player gets two poison counters. (A player with ten or more poison counters loses the game.)

Unctus's Retrofitter

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When this creature enters, up to one target artifact you control becomes an artifact creature with base power and toughness 4/4 for as long as this creature remains on the battlefield.

Experimental Augury

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Phyrexian Metamorph

({U/P} can be paid with either {U} or 2 life.)
You may have this creature enter as a copy of any artifact or creature on the battlefield, except it's an artifact in addition to its other types.

Necropede

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When this creature dies, you may put a -1/-1 counter on target creature.

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Viral Drake

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Curie, Emergent Intelligence

Whenever Curie deals combat damage to a player, draw cards equal to its base power.
{1}{U}, Exile another nontoken artifact creature you control: Curie becomes a copy of the exiled creature, except it has "Whenever this creature deals combat damage to a player, draw cards equal to its base power."

Aspirant's Ascent

Until end of turn, target creature gets +1/+3 and gains flying and toxic 1. (Players dealt combat damage by that creature also get a poison counter.)

Prologue to Phyresis

Each opponent gets a poison counter.
Draw a card.

Corrupted Resolve

Counter target spell if its controller is poisoned.

Bring the Ending

Counter target spell unless its controller pays {2}.
Corrupted — Counter that spell instead if its controller has three or more poison counters.

Distorted Curiosity

Corrupted — This spell costs {2} less to cast if an opponent has three or more poison counters.
Draw two cards.

Vivisurgeon's Insight

Draw three cards. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Psychosis Crawler

Psychosis Crawler's power and toughness are each equal to the number of cards in your hand.
Whenever you draw a card, each opponent loses 1 life.