Necromantic Thirst

Enchant creature
Whenever enchanted creature deals combat damage to a player, you may return target creature card from your graveyard to your hand.

Gixian Infiltrator

Whenever you sacrifice another permanent, put a +1/+1 counter on Gixian Infiltrator.

Long Goodbye

This spell can't be countered. (This includes by the ward ability.)
Destroy target creature or planeswalker with mana value 3 or less.

Murder

Live or Die

Choose one —
• Return target creature card from your graveyard to the battlefield.
• Destroy target creature.

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Mirrodin Avenged

Destroy target creature that was dealt damage this turn.
Draw a card.

Grim Discovery

Choose one or both —
• Return target creature card from your graveyard to your hand.
• Return target land card from your graveyard to your hand.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Arcane Signet

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

Skithiryx, the Blight Dragon

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Skithiryx, the Blight Dragon gains haste until end of turn.
{B}{B}: Regenerate Skithiryx.

Swamp

Rotten Reunion

Exile up to one target card from a graveyard. Create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Accursed Marauder

When Accursed Marauder enters, each player sacrifices a nontoken creature of their choice.

Gix, Yawgmoth Praetor

Whenever a creature deals combat damage to one of your opponents, its controller may pay 1 life. If they do, they draw a card.
{4}{B}{B}{B}, Discard X cards: Exile the top X cards of target opponent's library. You may play lands and cast spells from among cards exiled this way without paying their mana costs.

Champion of the Perished

Whenever another Zombie you control enters, put a +1/+1 counter on Champion of the Perished.

Case of the Stashed Skeleton

When this Case enters, create a 2/1 black Skeleton creature token and suspect it. (It has menace and can't block.)
To solve — You control no suspected Skeletons. (If unsolved, solve at the beginning of your end step.)
Solved — {1}{B}, Sacrifice this Case: Search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Sol Ring

Touch of Moonglove

Target creature you control gets +1/+0 and gains deathtouch until end of turn. Whenever a creature dealt damage by that creature dies this turn, its controller loses 2 life. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

The Dross Pits

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

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.