Unspeakable Symbol

Pay 3 life: Put a +1/+1 counter on target creature.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Dark Confidant

At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Mister Negative

Vigilance, lifelink
Darkforce Inversion — When Mister Negative enters, you may exchange life totals with target opponent. If you lose life this way, draw that many cards.

Cecil, Redeemed Paladin

Lifelink
Protect — Whenever Cecil attacks, other attacking creatures gain indestructible until end of turn.

Cecil, Dark Knight

Deathtouch
Darkness — Whenever Cecil deals damage, you lose that much life. Then if your life total is less than or equal to half your starting life total, untap Cecil and transform it.

Cecil, Dark Knight // Cecil, Redeemed Paladin

Sign in Blood

Target player draws two cards and loses 2 life.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Black Market Connections

At the beginning of your first main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It is every creature type.)

Darkstar Augur

Offspring {B} (You may pay an additional {B} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Flying
At the beginning of your upkeep, reveal the top card of your library and put that card into your hand. You lose life equal to its mana value.

Bahamut, Warden of Light

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Wings of Light — Put a +1/+1 counter on each other creature you control. Those creatures gain flying until end of turn.
III — Gigaflare — Destroy target permanent. Exile Bahamut, then return it to the battlefield (front face up).
Flying

Dion, Bahamut's Dominant

Dragonfire Dive — During your turn, Dion and other Knights you control have flying.
When Dion enters, create a 2/2 white Knight creature token.
{4}{W}{W}, {T}: Exile Dion, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery.

Dion, Bahamut's Dominant // Bahamut, Warden of Light

Pact Weapon

As long as this Equipment is attached to a creature, you don't lose the game for having 0 or less life.
Whenever equipped creature attacks, draw a card and reveal it. The creature gets +X/+X until end of turn and you lose X life, where X is that card's mana value.
Equip—Discard a card.

Repay in Kind

Each player's life total becomes the lowest life total among all players.

Kain, Traitorous Dragoon

Jump — During your turn, Kain has flying.
Whenever Kain deals combat damage to a player, that player gains control of Kain. If they do, you draw that many cards, create that many tapped Treasure tokens, then lose that much life.

Lotho, Corrupt Shirriff

Whenever a player casts their second spell each turn, you lose 1 life and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Night's Whisper

Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Children of Korlis

Sacrifice this creature: You gain life equal to the life you've lost this turn. (Damage causes loss of life.)