Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control. Round up each time.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Astarion, the Decadent

Deathtouch, lifelink
At the beginning of your end step, choose one —
• Feed — Target opponent loses life equal to the amount of life they lost this turn.
• Friends — You gain life equal to the amount of life you gained this turn.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Mortify

Indulging Patrician

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of your end step, if you gained 3 or more life this turn, each opponent loses 3 life.

Orzhov Guildgate

Orzhov Guildgate enters tapped.
{T}: Add {W} or {B}.

Keen Duelist

At the beginning of your upkeep, you and target opponent each reveal the top card of your library. You each lose life equal to the mana value of the card revealed by the other player. You each put the card you revealed into your hand.

Scourge of the Skyclaves

Kicker {4}{B}
When you cast this spell, if it was kicked, each player loses half their life, rounded up.
Scourge of the Skyclaves's power and toughness are each equal to 20 minus the highest life total among players.

Soul Warden

Whenever another creature enters, you gain 1 life.

Sol Ring

Command Tower

Scytheclaw

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, that player loses half their life, rounded up.
Equip {3}

Ambition's Cost

You draw three cards and you lose 3 life.

Shambling Vent

Shambling Vent enters tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Shambling Vent becomes a 2/3 white and black Elemental creature with lifelink until end of turn. It's still a land.

Pristine Talisman

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

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.)

Swamp

Boon Reflection

If you would gain life, you gain twice that much life instead.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel 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.)

Life Insurance

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.)
Whenever a nontoken creature dies, you lose 1 life and create a Treasure token.

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.)

Markov Purifier

Lifelink
At the beginning of your end step, if you gained life this turn, you may pay {2}. If you do, draw a card.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Felidar Sovereign

Vigilance, lifelink
At the beginning of your upkeep, if you have 40 or more life, you win the game.

Cliffhaven Vampire

Flying
Whenever you gain life, each opponent loses 1 life.

Fellwar Stone

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Rhox Faithmender

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
If you would gain life, you gain twice that much life instead.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Dire Fleet Ravager

Menace, deathtouch
When Dire Fleet Ravager enters, each player loses a third of their life, rounded up.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Ondu Skyruins

Ondu Skyruins enters tapped.
{T}: Add {W}.

Ondu Inversion

Ondu Inversion // Ondu Skyruins

Wound Reflection

At the beginning of each end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Exquisite Blood

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

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Vampire Nighthawk

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Read the Bones

Scry 2, then draw two cards. You lose 2 life.

Sorin Markov

+2: Sorin Markov deals 2 damage to any target and you gain 2 life.
−3: Target opponent's life total becomes 10.
−7: You control target player during that player's next turn.

Wrath of God

Destroy all creatures. They can't be regenerated.

Greed

Plains

Blood Tribute

Kicker—Tap an untapped Vampire you control. (You may tap a Vampire you control in addition to any other costs as you cast this spell.)
Target opponent loses half their life, rounded up. If this spell was kicked, you gain life equal to the life lost this way.

Sanguine Bond

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

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Cruel Celebrant

Whenever Cruel Celebrant or another creature or planeswalker you control dies, each opponent loses 1 life and you gain 1 life.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.