Siegfried, Famed Swordsman

Menace
When Siegfried enters, mill three cards. Then put X +1/+1 counters on Siegfried, where X is twice the number of creature cards in your graveyard.

Shinra Reinforcements

When this creature enters, mill three cards and you gain 3 life. (To mill three cards, put the top three cards of your library into your graveyard.)

Lychguard

Guardian Protocols — {3}{B}, Sacrifice this creature: Return all legendary creature cards from your graveyard to your hand.

Mire Triton

Deathtouch
When this creature enters, mill two cards and you gain 2 life. (To mill a card, put the top card of your library into your graveyard.)

Strangling Grasp

Enchant creature or planeswalker an opponent controls
At the beginning of your upkeep, enchanted permanent's controller sacrifices a nonland permanent of their choice, then that player loses 1 life.

Vengeful Strangler

This creature can't block.
When this creature dies, return it to the battlefield transformed under your control attached to target creature or planeswalker an opponent controls.

Vengeful Strangler // Strangling Grasp

Shadow, Mysterious Assassin

Deathtouch
Throw — Whenever Shadow deals combat damage to a player, you may sacrifice another nonland permanent. If you do, draw two cards and each opponent loses life equal to the mana value of the sacrificed permanent.

Swamp

Songs of the Damned

Add {B} for each creature card in your graveyard.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Avenger of the Fallen

Deathtouch
Mobilize X, where X is the number of creature cards in your graveyard. (Whenever this creature attacks, create X tapped and attacking 1/1 red Warrior creature tokens. Sacrifice them at the beginning of the next end step.)

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Merciless Executioner

When this creature enters, each player sacrifices a creature of their choice.

Royal Assassin

Nightblade Brigade

Deathtouch
Mobilize 1 (Whenever this creature attacks, create a tapped and attacking 1/1 red Warrior creature token. Sacrifice it at the beginning of the next end step.)
When this creature enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Diabolic Edict

Target player sacrifices a creature of their choice.

Sautekh Immortal

Flash
Elite Troops — This creature enters with a +1/+1 counter on it for each creature that died this turn.

Qarsi Revenant

Flying, deathtouch, lifelink
Renew — {2}{B}, Exile this card from your graveyard: Put a flying counter, a deathtouch counter, and a lifelink counter on target creature. Activate only as a sorcery.

Sephiroth, One-Winged Angel

Flying
Super Nova — As this creature transforms into Sephiroth, One-Winged Angel, you get an emblem with "Whenever a creature dies, target opponent loses 1 life and you gain 1 life."
Whenever Sephiroth attacks, you may sacrifice any number of other creatures. If you do, draw that many cards.

Sephiroth, Fabled SOLDIER

Whenever Sephiroth enters or attacks, you may sacrifice another creature. If you do, draw a card.
Whenever another creature dies, target opponent loses 1 life and you gain 1 life. If this is the fourth time this ability has resolved this turn, transform Sephiroth.

Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel

Venerated Stormsinger

Mobilize 1 (Whenever this creature attacks, create a tapped and attacking 1/1 red Warrior creature token. Sacrifice it at the beginning of the next end step.)
Whenever this creature or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Stitcher's Supplier

When this creature enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)

Dark Ritual

Daggerfang Duo

Deathtouch
When this creature enters, you may mill two cards. (You may put the top two cards of your library into your graveyard.)

Sheoldred, the Apocalypse

Deathtouch
Whenever you draw a card, you gain 2 life.
Whenever an opponent draws a card, they lose 2 life.

Not Dead After All

Until end of turn, target creature you control gains "When this creature dies, return it to the battlefield tapped under its owner's control, then create a Wicked Role token attached to it." (Enchanted creature gets +1/+1. When this token is put into a graveyard, each opponent loses 1 life.)

Priest of Gix

When this creature enters, add {B}{B}{B}.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Fleshbag Marauder

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)