Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Shizo, Death's Storehouse

{T}: Add {B}.
{B}, {T}: Target legendary creature gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Profane Tutor

Suspend 2—{1}{B} (Rather than cast this card from your hand, pay {1}{B} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Search your library for a card, put that card into your hand, then shuffle.

Champion's Helm

Equipped creature gets +2/+2.
As long as equipped creature is legendary, it has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Blanket of Night

Each land is a Swamp in addition to its other land types.

Crumbling Ashes

At the beginning of your upkeep, destroy target creature with a -1/-1 counter on it.

Swamp

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your hand.

Shirei, Shizo's Caretaker

Whenever a creature with power 1 or less is put into your graveyard from the battlefield, you may return that card to the battlefield at the beginning of the next end step if Shirei, Shizo's Caretaker is still on the battlefield.

Whispering Specter

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Whispering Specter deals combat damage to a player, you may sacrifice it. If you do, that player discards a card for each poison counter they have.

Jet Medallion

Black spells you cast cost {1} less to cast.

Orzhov Enforcer

Deathtouch
Afterlife 1 (When this creature dies, create a 1/1 white and black Spirit creature token with flying.)

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Fume Spitter

Sacrifice Fume Spitter: Put a -1/-1 counter on target creature.

Leechridden Swamp

({T}: Add {B}.)
Leechridden Swamp enters tapped.
{B}, {T}: Each opponent loses 1 life. Activate only if you control two or more black permanents.

Witch's Cauldron

{1}{B}, {T}, Sacrifice a creature: You gain 1 life and draw a card.

Death Cultist

Sacrifice Death Cultist: Target player loses 1 life and you gain 1 life.

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Mire's Toll

Target player reveals a number of cards from their hand equal to the number of Swamps you control. You choose one of them. That player discards that card.

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Volrath's Stronghold

{T}: Add {C}.
{1}{B}, {T}: Put target creature card from your graveyard on top of your library.