Gisa, Glorious Resurrector

If a creature an opponent controls would die, exile it instead.
At the beginning of your upkeep, put all creature cards exiled with Gisa, Glorious Resurrector onto the battlefield under your control. They gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Athreos, Shroud-Veiled

Indestructible
As long as your devotion to white and black is less than seven, Athreos isn't a creature.
At the beginning of your end step, put a coin counter on another target creature.
Whenever a creature with a coin counter on it dies or is put into exile, return that card to the battlefield under your control.

Monk of the Open Hand

Flurry of Blows — Whenever you cast your second spell each turn, put a +1/+1 counter on Monk of the Open Hand.

Doomskar Oracle

Whenever you cast your second spell each turn, you gain 2 life.
Foretell {W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Killian, Ink Duelist

Lifelink
Menace (This creature can't be blocked except by two or more creatures.)
Spells you cast that target a creature cost {2} less to cast.

Falkenrath Noble

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

Stab Wound

Enchant creature
Enchanted creature gets -2/-2.
At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.

Lorcan, Warlock Collector

Flying
Whenever a creature card is put into an opponent's graveyard from anywhere, you may pay life equal to its mana value. If you do, put it onto the battlefield under your control. It's a Warlock in addition to its other types.
If a Warlock you control would die, exile it instead.

Bloodsky Berserker

Whenever you cast your second spell each turn, put two +1/+1 counters on Bloodsky Berserker. It gains menace until end of turn. (It can't be blocked except by two or more creatures.)

Wretched Confluence

Choose three. You may choose the same mode more than once.
• Target player draws a card and loses 1 life.
• Target creature gets -2/-2 until end of turn.
• Return target creature card from your graveyard to your hand.

Soul Bleed

Enchant creature
At the beginning of the upkeep of enchanted creature's controller, that player loses 1 life.

Morbid Opportunist

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

Nettlevine Blight

Enchant creature or land
Enchanted permanent has "At the beginning of your end step, sacrifice this permanent and attach Nettlevine Blight to a creature or land you control."

Pontiff of Blight

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Other creatures you control have extort. (If a creature has multiple instances of extort, each triggers separately.)

Tithe Drinker

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Clarion Spirit

Whenever you cast your second spell each turn, create a 1/1 white Spirit creature token with flying.

Enslave

Enchant creature
You control enchanted creature.
At the beginning of your upkeep, enchanted creature deals 1 damage to its owner.

Blood Artist

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

Warlock Class

(Gain the next level as a sorcery to add its ability.)
At the beginning of your end step, if a creature died this turn, each opponent loses 1 life.
{1}{B}: Level 2
When this Class becomes level 2, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{6}{B}: Level 3
At the beginning of your end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Professor Onyx

Magecraft — Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life.
+1: You lose 1 life. Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
−3: Each opponent sacrifices a creature with the greatest power among creatures that player controls.
−8: Each opponent may discard a card. If they don't, they lose 3 life. Repeat this process six more times.

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.)

Parasitic Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, its controller loses 2 life and you gain 2 life.

Mind Whip

Enchant creature
At the beginning of the upkeep of enchanted creature's controller, that player may pay {3}. If they don't, Mind Whip deals 2 damage to that player and you tap that creature.

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.

Contaminated Bond

Enchant creature (Target a creature as you cast this. This card enters the battlefield attached to that creature.)
Whenever enchanted creature attacks or blocks, its controller loses 3 life.

Parasitic Bond

Enchant creature
At the beginning of the upkeep of enchanted creature's controller, Parasitic Bond deals 2 damage to that player.

Deathbringer Liege

Other white creatures you control get +1/+1.
Other black creatures you control get +1/+1.
Whenever you cast a white spell, you may tap target creature.
Whenever you cast a black spell, you may destroy target creature if it's tapped.