Deathreap Ritual

Morbid — At the beginning of each end step, if a creature died this turn, you may draw a card.

Ob Nixilis, Unshackled

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.

Tainted Aether

Whenever a creature enters, its controller sacrifices a creature or land of their choice.

Demon of Dark Schemes

Flying
When Demon of Dark Schemes enters, all other creatures get -2/-2 until end of turn.
Whenever another creature dies, you get {E} (an energy counter).
{2}{B}, Pay {E}{E}{E}{E}: Put target creature card from a graveyard onto the battlefield under your control tapped.

Birds of Paradise

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.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your first main phase, add {B} for each charge counter on Black Market.

Plague Engineer

Deathtouch
As Plague Engineer enters, choose a creature type.
Creatures of the chosen type your opponents control get -1/-1.

Night of Souls' Betrayal

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.

Vampiric Rites

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

Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Elvish Mystic

Virulent Plague

Grismold, the Dreadsower

Trample
At the beginning of your end step, each player creates a 1/1 green Plant creature token.
Whenever a creature token dies, put a +1/+1 counter on Grismold, the Dreadsower.

Illness in the Ranks

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Tendershoot Dryad

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
At the beginning of each upkeep, create a 1/1 green Saproling creature token.
Saprolings you control get +2/+2 as long as you have the city's blessing.

Poison-Tip Archer

Reach (This creature can block creatures with flying.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Whenever another creature dies, each opponent loses 1 life.

Moldervine Reclamation

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

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Sylvan Offering

Choose an opponent. You and that player each create an X/X green Treefolk creature token.
Choose an opponent. You and that player each create X 1/1 green Elf Warrior creature tokens.

Ashnod's Altar

Dictate of Erebos

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

Ophiomancer

At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch.

Engineered Plague

As Engineered Plague enters, choose a creature type.
All creatures of the chosen type get -1/-1.