Pit Keeper

When Pit Keeper enters, if you have four or more creature cards in your graveyard, you may return target creature card from your graveyard to your hand.

Yawgmoth, Thran Physician

Protection from Humans
Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.
{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Damnation

Destroy all creatures. They can't be regenerated.

Nightshade Assassin

First strike
When Nightshade Assassin enters, you may reveal X black cards in your hand. If you do, target creature gets -X/-X until end of turn.
Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Gorgon Recluse

Whenever Gorgon Recluse blocks or becomes blocked by a nonblack creature, destroy that creature at end of combat.
Madness {B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Cutthroat il-Dal

Hellbent — Cutthroat il-Dal has shadow as long as you have no cards in hand. (It can block or be blocked by only creatures with shadow.)

Sangrophage

At the beginning of your upkeep, tap Sangrophage unless you pay 2 life.

Swamp

Deepcavern Imp

Flying, haste
Echo—Discard a card. (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Urborg Syphon-Mage

{2}{B}, {T}, Discard a card: Each other player loses 2 life. You gain life equal to the life lost this way.

Lotus Bloom

Suspend 3—{0} (Rather than cast this card from your hand, pay {0} and exile it with three 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.)
{T}, Sacrifice Lotus Bloom: Add three mana of any one color.

Blightspeaker

{T}: Target player loses 1 life.
{4}, {T}: Search your library for a Rebel permanent card with mana value 3 or less, put it onto the battlefield, then shuffle.

Assassinate

Psychotic Episode

Target player reveals their hand and the top card of their library. You choose a card revealed this way. That player puts the chosen card on the bottom of their library.
Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Big Game Hunter

When Big Game Hunter enters, destroy target creature with power 4 or greater. It can't be regenerated.
Madness {B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Trespasser il-Vec

Discard a card: Trespasser il-Vec gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Smallpox

Each player loses 1 life, discards a card, sacrifices a creature, then sacrifices a land.