Necrosynthesis

Enchant creature
Enchanted creature has "Whenever another creature dies, put a +1/+1 counter on this creature."
When enchanted creature dies, look at the top X cards of your library, where X is its power. Put one of those cards into your hand and the rest on the bottom of your library in a random order.

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters the battlefield, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Mask of Griselbrand

Equipped creature has flying and lifelink.
Whenever equipped creature dies, you may pay X life, where X is its power. If you do, draw X cards.
Equip {3}

Vindictive Lich

When Vindictive Lich dies, choose one or more. Each mode must target a different player.
• Target opponent sacrifices a creature.
• Target opponent discards two cards.
• Target opponent loses 5 life.

Harvester of Souls

Deathtouch
Whenever another nontoken creature dies, you may draw a card.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Eternal Thirst

Enchant creature
Enchanted creature has lifelink and "Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature." (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Night's Whisper

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature.

Bone Splinters

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Open the Graves

Whenever a nontoken creature you control dies, create a 2/2 black Zombie creature token.

Junji, the Midnight Sky

Flying, menace
When Junji, the Midnight Sky dies, choose one —
• Each opponent discards two cards and loses 2 life.
• Put target non-Dragon creature card from a graveyard onto the battlefield under your control. You lose 2 life.

Agent of the Iron Throne

Commander creatures you own have "Whenever an artifact or creature you control is put into a graveyard from the battlefield, each opponent loses 1 life."

Drivnod, Carnage Dominus

If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{B/P}{B/P}, Exile three creature cards from your graveyard: Put an indestructible counter on Drivnod, Carnage Dominus. ({B/P} can be paid with either {B} or 2 life.)

Gixian Puppeteer

Whenever you draw your second card each turn, each opponent loses 2 life and you gain 2 life.
When Gixian Puppeteer dies, return another target creature card with mana value 3 or less from your graveyard to the battlefield.

Sangromancer

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Erebos, Bleak-Hearted

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature.
Whenever another creature you control dies, you may pay 2 life. If you do, draw a card.
{1}{B}, Sacrifice another creature: Target creature gets -2/-1 until end of turn.

Revel in Riches

Whenever a creature an opponent controls dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
At the beginning of your upkeep, if you control ten or more Treasures, you win the game.

Transmogrant's Crown

Equipped creature gets +2/+0.
Whenever equipped creature dies, draw a card.
Equip {2} or {B}

Offer Immortality

Target creature gains deathtouch and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Bastion of Remembrance

When Bastion of Remembrance enters the battlefield, create a 1/1 white Human Soldier creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Wurmcoil Larva

Deathtouch, lifelink
When Wurmcoil Larva dies, create a 1/2 black Phyrexian Wurm artifact creature token with deathtouch and a 2/1 black Phyrexian Wurm artifact creature token with lifelink.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Sol Ring

Caged Sun

As Caged Sun enters the battlefield, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Soul Shatter

Each opponent sacrifices a creature or planeswalker with the highest mana value among creatures and planeswalkers they control.

Tarrian's Soulcleaver

Equipped creature has vigilance.
Whenever another artifact or creature is put into a graveyard from the battlefield, put a +1/+1 counter on equipped creature.
Equip {2}

Feral Ghoul

Menace
Whenever another creature you control dies, put a +1/+1 counter on Feral Ghoul.
When Feral Ghoul dies, each opponent gets a number of rad counters equal to its power.

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature.

Weatherlight Compleated

Flying
As long as Weatherlight Compleated has four or more phyresis counters on it, it's a Phyrexian creature in addition to its other types.
Whenever a creature you control dies, put a phyresis counter on Weatherlight Compleated. Then draw a card if it has seven or more phyresis counters on it. If it doesn't, scry 1.

Kokusho, the Evening Star

Flying
When Kokusho, the Evening Star dies, each opponent loses 5 life. You gain life equal to the life lost this way.

Vindictive Vampire

Whenever another creature you control dies, Vindictive Vampire deals 1 damage to each opponent and you gain 1 life.

Necrogen Communion

Enchant creature you control
Enchanted creature has toxic 2. (Players dealt combat damage by it also get two poison counters.)
When enchanted creature dies, return that card to the battlefield under your control.

Rise of the Dark Realms

Put all creature cards from all graveyards onto the battlefield under your control.

Ogre Slumlord

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Blood for Bones

As an additional cost to cast this spell, sacrifice a creature.
Return a creature card from your graveyard to the battlefield, then return another creature card from your graveyard to your hand.

Novice Occultist

When Novice Occultist dies, you draw a card and you lose 1 life.

Wurmcoil Engine

Deathtouch, lifelink
When Wurmcoil Engine dies, create a 3/3 colorless Phyrexian Wurm artifact creature token with deathtouch and a 3/3 colorless Phyrexian Wurm artifact creature token with lifelink.

Morbid Opportunist

Whenever one or more other creatures die, draw a card. This ability triggers only once each turn.

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni, Undying Partisan.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Butcher of Malakir

Flying
Whenever Butcher of Malakir or another creature you control dies, each opponent sacrifices a creature.

Hero's Downfall

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Sanguinary Priest

Lifelink
Blood Chalice — Whenever another creature you control dies, Sanguinary Priest deals 1 damage to any target.

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.

Liliana, Dreadhorde General

Whenever a creature you control dies, draw a card.
+1: Create a 2/2 black Zombie creature token.
−4: Each player sacrifices two creatures.
−9: Each opponent chooses a permanent they control of each permanent type and sacrifices the rest.

Cavalier of Night

Lifelink
When Cavalier of Night enters the battlefield, you may sacrifice another creature. When you do, destroy target creature an opponent controls.
When Cavalier of Night dies, return target creature card with mana value 3 or less from your graveyard to the battlefield.

Bind Spirit

Return target creature card from your graveyard to your hand. (Then exile this card. You may cast the artifact later from exile.)

Ghost Lantern

Whenever a creature you control dies, put a +1/+1 counter on equipped creature.
Equip {1}

Ghost Lantern // Bind Spirit

Blight Mound

Attacking Pests you control get +1/+0 and have menace.
Whenever a nontoken creature you control dies, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."

Shambling Ghast

When Shambling Ghast dies, choose one —
• Brave the Stench — Target creature an opponent controls gets -1/-1 until end of turn.
• Search the Body — Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Body Launderer

Deathtouch
Whenever another nontoken creature you control dies, Body Launderer connives.
When Body Launderer dies, return another target non-Rogue creature card with equal or lesser power from your graveyard to the battlefield.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Falkenrath Noble

Flying
Whenever Falkenrath Noble or another creature dies, target player loses 1 life and you gain 1 life.

Disciple of Perdition

When Disciple of Perdition dies, choose one. If you have exactly 13 life, you may choose both.
• You draw a card and you lose 1 life.
• Exile target opponent's graveyard. That player loses 1 life.

Dark Prophecy

Whenever a creature you control dies, you draw a card and you lose 1 life.

Pawn of Ulamog

Whenever Pawn of Ulamog or another nontoken creature you control dies, you may create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.

The Meathook Massacre

When The Meathook Massacre enters the battlefield, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

Vein Ripper

Flying
Ward—Sacrifice a creature.
Whenever a creature dies, target opponent loses 2 life and you gain 2 life.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Doomed Dissenter

When Doomed Dissenter dies, create a 2/2 black Zombie creature token.

Carrier Thrall

When Carrier Thrall dies, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this creature: Add {C}."