Thermo-Alchemist

Defender
{T}: This creature deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap this creature.

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.)

Sabotender

Reach
Landfall — Whenever a land you control enters, this creature deals 1 damage to each opponent.

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Soot Imp

Flying
Whenever a player casts a nonblack spell, that player loses 1 life.

Avalanche of Sector 7

Menace
Avalanche of Sector 7's power is equal to the number of artifacts your opponents control.
Whenever an opponent activates an ability of an artifact they control, Avalanche of Sector 7 deals 1 damage to that player.

Firebrand Archer

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Creeping Bloodsucker

At the beginning of your upkeep, this creature deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Kessig Flamebreather

Unstable Amulet

When this artifact enters, you get {E}{E} (two energy counters).
Whenever you cast a spell from anywhere other than your hand, this artifact deals 1 damage to each opponent.
{T}, Pay {E}{E}: Exile the top card of your library. You may play it until you exile another card with this artifact.

Prosper, Tome-Bound

Deathtouch
Mystic Arcanum — At the beginning of your end step, exile the top card of your library. Until the end of your next turn, you may play that card.
Pact Boon — Whenever you play a card from exile, create a Treasure token.

Kederekt Parasite

Whenever an opponent draws a card, if you control a red permanent, you may have this creature deal 1 damage to that player.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Ob Nixilis, Captive Kingpin

Flying, trample
Whenever one or more opponents each lose exactly 1 life, put a +1/+1 counter on Ob Nixilis. Exile the top card of your library. Until your next end step, you may play that card.

Blood Artist

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

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

All Will Be One

Whenever you put one or more counters on a permanent or player, this enchantment deals that much damage to target opponent, creature an opponent controls, or planeswalker an opponent controls.

Razorkin Needlehead

This creature has first strike during your turn.
Whenever an opponent draws a card, this creature deals 1 damage to them.

Fate Unraveler

Whenever an opponent draws a card, this creature deals 1 damage to that player.

Trance Kuja, Fate Defied

Flare Star — If a Wizard you control would deal damage to a permanent or player, it deals double that damage instead.

Kuja, Genome Sorcerer

At the beginning of your end step, create a tapped 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent." Then if you control four or more Wizards, transform Kuja.

Kuja, Genome Sorcerer // Trance Kuja, Fate Defied

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

Dark Ritual

Sanguine Bond

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

Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Scrawling Crawler

At the beginning of your upkeep, each player draws a card.
Whenever an opponent draws a card, that player loses 1 life.

Roiling Vortex

At the beginning of each player's upkeep, this enchantment deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, this enchantment deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Manabarbs

Whenever a player taps a land for mana, this enchantment deals 1 damage to that player.