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.

Golgari Locket

{T}: Add {B} or {G}.
{B/G}{B/G}{B/G}{B/G}, {T}, Sacrifice Golgari Locket: Draw two cards.

Forest

Phyrexian Atlas

{T}: Add one mana of any color.
Corrupted — Whenever Phyrexian Atlas becomes tapped, each opponent who has three or more poison counters loses 1 life.

Orzhov Locket

{T}: Add {W} or {B}.
{W/B}{W/B}{W/B}{W/B}, {T}, Sacrifice Orzhov Locket: Draw two cards.

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.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Golgari Cluestone

{T}: Add {B} or {G}.
{B}{G}, {T}, Sacrifice Golgari Cluestone: Draw a card.

Plains

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.

Birds of Paradise

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.

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Golgari Keyrune

{T}: Add {B} or {G}.
{B}{G}: Golgari Keyrune becomes a 2/2 black and green Insect artifact creature with deathtouch until end of turn.

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.

Vivisection Evangelist

Vigilance
Corrupted — When Vivisection Evangelist enters, if an opponent has three or more poison counters, destroy target creature or planeswalker an opponent controls.

Viral Spawning

Create a 3/3 green Phyrexian Beast creature token with toxic 1. (Players dealt combat damage by it also get a poison counter.)
Corrupted — As long as an opponent has three or more poison counters and Viral Spawning is in your graveyard, it has flashback {2}{G}. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Anointed Procession

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.

Tyrranax Rex

This spell can't be countered.
Trample, ward {4}, haste
Toxic 4 (Players dealt combat damage by this creature also get four 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.)

Blossoming Sands

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {G} or {W}.

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.

Arcane Signet

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

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.

Blooming Marsh

Blooming Marsh enters tapped unless you control two or fewer other lands.
{T}: Add {B} or {G}.

Goliath Hatchery

When Goliath Hatchery enters, create two 3/3 green Phyrexian Beast creature tokens with toxic 1. (Players dealt combat damage by them also get a poison counter.)
Corrupted — At the beginning of your upkeep, if an opponent has three or more poison counters, choose a creature you control, then draw cards equal to its total toxic value.

Plague Stinger

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

Swamp

Pestilent Syphoner

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

Orzhov Cluestone

{T}: Add {W} or {B}.
{W}{B}, {T}, Sacrifice Orzhov Cluestone: 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.)

Ichor Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When Ichor Rats enters, each player gets a poison counter.

Orzhov Guildgate

This land enters tapped.
{T}: Add {W} or {B}.

Bonepicker Skirge

Flying
Corrupted — As long as an opponent has three or more poison counters, Bonepicker Skirge has deathtouch and lifelink.

Binding the Old Gods

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Destroy target nonland permanent an opponent controls.
II — Search your library for a Forest card, put it onto the battlefield tapped, then shuffle.
III — Creatures you control gain deathtouch until end of turn.

Arctic Flats

Arctic Flats enters tapped.
{T}: Add {G} or {W}.

Abzan Banner

{T}: Add {W}, {B}, or {G}.
{W}{B}{G}, {T}, Sacrifice Abzan Banner: Draw a card.

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.

Archway Commons

Archway Commons enters tapped.
When Archway Commons enters, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.