Crypt Cobra

Whenever Crypt Cobra attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

Anoint with Affliction

Exile target creature if it has mana value 3 or less.
Corrupted — Exile that creature instead if its controller has three or more poison counters.

Cystbearer

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

Blightbelly Rat

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Blightbelly Rat dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Geth's Summons

Return up to one target creature card from your graveyard to the battlefield.
Corrupted — For each opponent who has three or more poison counters as you cast this spell, put up to one target creature card from that player's graveyard onto the battlefield under your control.

Carrion Call

Create two 1/1 green Phyrexian Insect creature tokens with infect. (They deal damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Chittering Skitterling

Corrupted — Sacrifice an artifact or creature: Draw a card. Activate only if an opponent has three or more poison counters and only once each turn.

Glissa's Retriever

Haste, toxic 3 (Players dealt combat damage by this creature also get three poison counters.)
Glissa's Retriever can't be blocked by creatures with power 2 or less.
Corrupted — When Glissa's Retriever dies, exile it. When you do, return up to X target cards from your graveyard to your hand, where X is the number of opponents who have three or more poison counters.

Branchblight Stalker

Toxic 2 (Players dealt combat damage by this creature also get two poison counters.)

Bloated Contaminator

Trample
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Whenever Bloated Contaminator deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Glistener Elf

Blackcleave Goblin

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

Feed the Infection

You draw three cards and you lose 3 life.
Corrupted — Each opponent who has three or more poison counters loses 3 life.

Annex Sentry

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Annex Sentry enters the battlefield, exile target artifact or creature an opponent controls with mana value 3 or less until Annex Sentry leaves the battlefield.

Snake Cult Initiation

Enchant creature
Enchanted creature has poisonous 3. (Whenever it deals combat damage to a player, that player gets three poison counters. A player with ten or more poison counters loses the game.)

Bilious Skulldweller

Deathtouch
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)

Blight Mamba

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{1}{G}: Regenerate Blight Mamba.

Decimator Web

{4}, {T}: Target opponent loses 2 life, gets a poison counter, then mills six cards.

Flensing Raptor

Flying
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Flensing Raptor enters the battlefield, another target creature you control with toxic gets +1/+1 and gains flying until end of turn.

Ajani, Sleeper Agent

Compleated ({G/W/P} can be paid with {G}, {W}, or 2 life. If life was paid, this planeswalker enters with two fewer loyalty counters.)
+1: Reveal the top card of your library. If it's a creature or planeswalker card, put it into your hand. Otherwise, you may put it on the bottom of your library.
−3: Distribute three +1/+1 counters among up to three target creatures. They gain vigilance until end of turn.
−6: You get an emblem with "Whenever you cast a creature or planeswalker spell, target opponent gets two poison counters."

Crawling Chorus

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Crawling Chorus dies, create a 1/1 colorless Phyrexian Mite artifact creature token with toxic 1 and "This creature can't block."

Flesh-Eater Imp

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Sacrifice a creature: Flesh-Eater Imp gets +1/+1 until end of turn.

Dune Mover

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Dune Mover enters the battlefield, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.

Contaminant Grafter

Trample, toxic 1
Whenever one or more creatures you control deal combat damage to one or more players, proliferate.
Corrupted — At the beginning of your end step, if an opponent has three or more poison counters, draw a card, then you may put a land card from your hand onto the battlefield.

Flensermite

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Core Prowler

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Core Prowler dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Contagious Nim

Charge of the Mites

Choose one —
• Charge of the Mites deals damage equal to the number of creatures you control to target creature or planeswalker.
• Create two 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block." (Players dealt combat damage by them also get a poison counter.)

Ixhel, Scion of Atraxa

Flying, vigilance, toxic 2
Corrupted — At the beginning of your end step, each opponent who has three or more poison counters exiles the top card of their library face down. You may look at and play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast those spells.