Ossification

Enchant basic land you control
When Ossification enters, exile target creature or planeswalker an opponent controls until Ossification leaves the battlefield.

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.

Basilica Shepherd

Flying
When Basilica Shepherd enters, 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.)

Jawbone Duelist

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

Annex Sentry

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

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.)

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.

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.

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters tapped unless you control two or more basic lands.

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.)

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."

Myr Convert

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
{T}, Pay 2 life: Add one mana of any color.

Necrogen Rotpriest

Toxic 2 (Players dealt combat damage by this creature also get two poison counters.)
Whenever a creature you control with toxic deals combat damage to a player, that player gets an additional poison counter.
{1}{B}{G}: Target creature you control with toxic gains deathtouch until end of turn.

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.)

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."