Barbed Servitor

Indestructible
When Barbed Servitor enters, suspect it. (It has menace and can't block.)
Whenever Barbed Servitor deals combat damage to a player, you draw a card and you lose 1 life.
Whenever Barbed Servitor is dealt damage, target opponent loses that much life.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Phyrexian Arena

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

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Sol Ring

Seizan, Perverter of Truth

At the beginning of each player's upkeep, that player loses 2 life and draws two cards.

Hero's Downfall

Breathe Your Last

Destroy target creature or planeswalker. You gain 1 life for each of its colors.

Ob Nixilis Reignited

+1: You draw a card and you lose 1 life.
−3: Destroy target creature.
−8: Target opponent gets an emblem with "Whenever a player draws a card, you lose 2 life."

Arcane Signet

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

Command Tower

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

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.

Voracious Fell Beast

Flying
When Voracious Fell Beast enters, each opponent sacrifices a creature. Create a Food token for each creature sacrificed this way. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Flare of Malice

You may sacrifice a nontoken black creature rather than pay this spell's mana cost.
Each opponent sacrifices a creature or planeswalker with the greatest mana value among creatures and planeswalkers they control.