Swamp

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.

Bonepicker Skirge

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

Vraan, Executioner Thane

Whenever one or more other creatures you control die, each opponent loses 2 life and you gain 2 life. This ability triggers only once each turn.

Thriving Moor

Thriving Moor enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Pestilent Syphoner

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

Testament Bearer

When Testament Bearer dies, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Ambulatory Edifice

When Ambulatory Edifice enters, you may pay 2 life. When you do, target creature gets -1/-1 until end of turn.

Nimraiser Paladin

Toxic 2 (Players dealt combat damage by this creature also get two poison counters.)
When Nimraiser Paladin enters, return target creature card with mana value 3 or less from your graveyard to your hand.

Drown in Ichor

Target creature gets -4/-4 until end of turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Annihilating Glare

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature or planeswalker.

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.

The Dross Pits

The Dross Pits enters tapped.
{T}: Add {B}.
{1}{B}, {T}, Sacrifice The Dross Pits: Draw a card.

Dross Skullbomb

{1}, Sacrifice Dross Skullbomb: Draw a card.
{2}{B}, Sacrifice Dross Skullbomb: Return target creature card from your graveyard to your hand. Draw a card. Activate only as a sorcery.

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.)