Contagion Clasp

When Contagion Clasp enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Prologue to Phyresis

Each opponent gets a poison counter.
Draw a card.

Tainted Observer

Flying
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Whenever another creature you control enters, you may pay {2}. If you do, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Glistener Elf

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

Prosthetic Injector

Equipped creature gets +0/+2 and has toxic 1. (Players dealt combat damage by equipped creature also get a poison counter.)
Equip {1}

Grafted Exoskeleton

Equipped creature gets +2/+2 and has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Grafted Exoskeleton becomes unattached from a permanent, sacrifice that permanent.
Equip {2}

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.

Tamiyo, Compleated Sage

Compleated ({G/U/P} can be paid with {G}, {U}, or 2 life. If life was paid, this planeswalker enters with two fewer loyalty counters.)
+1: Tap up to one target artifact or creature. It doesn't untap during its controller's next untap step.
−X: Exile target nonland permanent card with mana value X from your graveyard. Create a token that's a copy of that card.
−7: Create Tamiyo's Notebook, a legendary colorless artifact token with "Spells you cast cost {2} less to cast" and "{T}: Draw a card."

Norn's Choirmaster

Flying, first strike
Whenever a commander you control enters or attacks, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.)

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Kinzu of the Bleak Coven

Flying
Whenever another nontoken creature you control dies, you may pay 2 life and exile it. If you do, create a token that's a copy of that creature, except it's 1/1 and has toxic 1. (Players dealt combat damage by it also get a poison counter.)

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."

Phyresis Outbreak

Each opponent gets a poison counter. Then each creature your opponents control gets -1/-1 until end of turn for each poison counter its controller has.

Merciless Eviction

Choose one —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all planeswalkers.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Infectious Inquiry

You draw two cards and you lose 2 life. Each opponent gets a poison counter.

Mirari's Wake

Creatures you control get +1/+1.
Whenever you tap a land for mana, add one mana of any type that land produced.

Fateful Absence

Destroy target creature or planeswalker. Its controller investigates. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Fynn, the Fangbearer

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

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.

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.

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."

Norn's Decree

Whenever one or more creatures an opponent controls deal combat damage to you, that opponent gets a poison counter.
Whenever a player attacks, if one or more players being attacked are poisoned, the attacking player draws a card.

Grateful Apparition

Flying
Whenever Grateful Apparition deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Vraska's Fall

Each opponent sacrifices a creature or planeswalker of their choice and gets a poison counter.

Jawbone Duelist

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

Triumph of the Hordes

Until end of turn, creatures you control get +1/+1 and gain trample and infect. (Creatures with infect deal damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Flux Channeler

Whenever you cast a noncreature spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Expand the Sphere

Look at the top six cards of your library. Put up to two land cards from among them onto the battlefield tapped and the rest on the bottom of your library in a random order. If you put fewer than two lands onto the battlefield this way, proliferate a number of times equal to the difference. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Merfolk Skydiver

Flying
When Merfolk Skydiver enters, put a +1/+1 counter on target creature you control.
{3}{G}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.)

Distorted Curiosity

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

Vraska, Betrayal's Sting

Compleated ({B/P} can be paid with {B} or 2 life. If life was paid, this planeswalker enters with two fewer loyalty counters.)
0: You draw a card and you lose 1 life. Proliferate.
−2: Target creature becomes a Treasure artifact with "{T}, Sacrifice this artifact: Add one mana of any color" and loses all other card types and abilities.
−9: If target player has fewer than nine poison counters, they get a number of poison counters equal to the difference.

Glistening Sphere

Glistening Sphere enters tapped.
When Glistening Sphere enters, proliferate.
{T}: Add one mana of any color.
Corrupted — {T}: Add three mana of any one color. Activate only if an opponent has three or more poison counters.

Slaughter Singer

Toxic 2 (Players dealt combat damage by this creature also get two poison counters.)
Whenever another creature you control with toxic attacks, it gets +1/+1 until end of turn.

Phyrexian Swarmlord

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, create a 1/1 green Phyrexian Insect creature token with infect for each poison counter your opponents have.

Necrogen Communion

Enchant creature you control
Enchanted creature has toxic 2. (Players dealt combat damage by it also get two poison counters.)
When enchanted creature dies, return that card to the battlefield under your control.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Venerated Rotpriest

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Whenever a creature you control becomes the target of a spell, target opponent gets a poison counter.

Unnatural Restoration

Return target permanent card from your graveyard to your hand. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Sol Ring

Noxious Revival

({G/P} can be paid with either {G} or 2 life.)
Put target card from a graveyard on top of its owner's library.

Bilious Skulldweller

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

Infectious Bite

Target creature you control deals damage equal to its power to target creature you don't control. Each opponent gets a poison counter.

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.

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Corrupted Resolve

Counter target spell if its controller is poisoned.

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.

Tymna the Weaver

Lifelink
At the beginning of each of your postcombat main phases, you may pay X life, where X is the number of opponents that were dealt combat damage this turn. If you do, draw X cards.
Partner (You can have two commanders if both have partner.)

Park Heights Maverick

Dethrone (Whenever this creature attacks the player with the most life or tied for the most life, put a +1/+1 counter on it.)
Park Heights Maverick can't be blocked by creatures with power 2 or less.
Whenever Park Heights Maverick deals combat damage to a player or dies, proliferate.

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.)

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.)

Thrasios, Triton Hero

{4}: Scry 1, then reveal the top card of your library. If it's a land card, put it onto the battlefield tapped. Otherwise, draw a card.
Partner (You can have two commanders if both have partner.)

Vishgraz, the Doomhive

Menace, toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Vishgraz, the Doomhive enters, create three 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block."
Vishgraz gets +1/+1 for each poison counter your opponents have.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Skrelv, Defector Mite

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Skrelv, Defector Mite can't block.
{W/P}, {T}: Choose a color. Another target creature you control gains toxic 1 and hexproof from that color until end of turn. It can't be blocked by creatures of that color this turn. ({W/P} can be paid with either {W} or 2 life.)