Patchwork Gnomes

Discard a card: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Olivia's Dragoon

Discard a card: This creature gains flying until end of turn.

Terrus Wurm

Scavenge {6}{B} ({6}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Cabal Initiate

Discard a card: This creature gains lifelink until end of turn.
Threshold — This creature gets +1/+2 as long as seven or more cards are in your graveyard.

Fodder Tosser

{T}, Discard a card: This artifact deals 2 damage to target player or planeswalker.

Putrid Imp

Discard a card: This creature gains flying until end of turn.
Threshold — As long as seven or more cards are in your graveyard, this creature gets +1/+1 and can't block.

Girder Goons

When this creature dies, create a tapped 2/2 black Rogue creature token.
Blitz {3}{B} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Marshmist Titan

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

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.

Silumgar Scavenger

Flying
Exploit (When this creature enters, you may sacrifice a creature.)
Whenever another creature you control dies, put a +1/+1 counter on this creature. It gains haste until end of turn if it exploited that creature.

Oblivion Crown

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature has "Discard a card: This creature gets +1/+1 until end of turn."

Undertaker

{B}, {T}, Discard a card: Return target creature card from your graveyard to your hand.

Gloom Sower

Whenever this creature becomes blocked by a creature, that creature's controller loses 2 life and you gain 2 life.

Corpse Hauler

{2}{B}, Sacrifice this creature: Return another target creature card from your graveyard to your hand.

Gray Merchant of Asphodel

When this creature 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.)

Vampire Hounds

Discard a creature card: This creature gets +2/+2 until end of turn.

Cadaver Imp

Flying
When this creature enters, you may return target creature card from your graveyard to your hand.

Swamp

Dutiful Attendant

When this creature dies, return another target creature card from your graveyard to your hand.

Whisper, Blood Liturgist

{T}, Sacrifice two creatures: Return target creature card from your graveyard to the battlefield.

Jalum Tome

{2}, {T}: Draw a card, then discard a card.

Ulamog's Crusher

Annihilator 2 (Whenever this creature attacks, defending player sacrifices two permanents of their choice.)
This creature attacks each combat if able.

Fledgling Imp

{B}, Discard a card: This creature gains flying until end of turn.

Pit Keeper

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

Sanitarium Skeleton

{2}{B}: Return this card from your graveyard to your hand.

Hell Mongrel

Discard a card: This creature gets +1/+1 until end of turn.
Madness {2}{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.)

Twisted Abomination

{B}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Eldrazi Devastator

Baleful Beholder

When this creature enters, choose one —
• Antimagic Cone — Each opponent sacrifices an enchantment of their choice.
• Fear Ray — Creatures you control gain menace until end of turn. (A creature with menace can't be blocked except by two or more creatures.)

Ghastly Death Tyrant

When this creature enters, choose one —
• Disintegration Ray — Destroy target enchantment an opponent controls. You lose life equal to its mana value.
• Death Ray — Creatures you control gain deathtouch until end of turn.

Diregraf Horde

When this creature enters, create two 2/2 black Zombie creature tokens with decayed. When you do, exile up to two target cards from graveyards. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Gravedigger

When this creature enters, you may return target creature card from your graveyard to your hand.