Seizures

Enchant creature
Whenever enchanted creature becomes tapped, this Aura deals 3 damage to that creature's controller unless that player pays {3}.

Immolation Shaman

Whenever an opponent activates an ability of an artifact, creature, or land that isn't a mana ability, this creature deals 1 damage to that player.
{3}{R}{R}: This creature gets +3/+3 and gains menace until end of turn.

Cemetery Gatekeeper

First strike
When this creature enters, exile a card from a graveyard.
Whenever a player plays a land or casts a spell, if it shares a card type with the exiled card, this creature deals 2 damage to that player.

Scytheclaw Raptor

Whenever a player casts a spell, if it's not their turn, this creature deals 4 damage to them.

Pyrostatic Pillar

Whenever a player casts a spell with mana value 3 or less, this enchantment deals 2 damage to that player.

Spellshock

Whenever a player casts a spell, this enchantment deals 2 damage to that player.

Underworld Dreams

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

Psychogenic Probe

Whenever a spell or ability causes a player to shuffle their library, this artifact deals 2 damage to that player.

Eidolon of the Great Revel

Whenever a player casts a spell with mana value 3 or less, this creature deals 2 damage to that player.

Last Laugh

Whenever a permanent other than this enchantment is put into a graveyard from the battlefield, this enchantment deals 1 damage to each creature and each player.
When no creatures are on the battlefield, sacrifice this enchantment.

Haunting Wind

Whenever an artifact becomes tapped or a player activates an artifact's ability without {T} in its activation cost, this enchantment deals 1 damage to that artifact's controller.

Mogis, God of Slaughter

Indestructible
As long as your devotion to black and red is less than seven, Mogis isn't a creature.
At the beginning of each opponent's upkeep, Mogis deals 2 damage to that player unless they sacrifice a creature of their choice.

Dwarven Shrine

Whenever a player casts a spell, this enchantment deals X damage to that player, where X is twice the number of cards in all graveyards with the same name as that spell.

Fate Unraveler

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

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, this creature deals 2 damage to that player.

Spiteful Visions

At the beginning of each player's draw step, that player draws an additional card.
Whenever a player draws a card, this enchantment deals 1 damage to that player.

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

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.

Sunspine Lynx

Players can't gain life.
Damage can't be prevented.
When this creature enters, it deals damage to each player equal to the number of nonbasic lands that player controls.

Steam Vines

Enchant land
When enchanted land becomes tapped, destroy it and this Aura deals 1 damage to that land's controller. That player attaches this Aura to a land of their choice.

Manabarbs

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

Burning Earth

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

Screaming Nemesis

Haste
Whenever this creature is dealt damage, it deals that much damage to any other target. If a player is dealt damage this way, they can't gain life for the rest of the game.

Hearthborn Battler

Haste
Whenever a player casts their second spell each turn, this creature deals 2 damage to target opponent.

Plague Spitter

At the beginning of your upkeep, this creature deals 1 damage to each creature and each player.
When this creature dies, it deals 1 damage to each creature and each player.

Ash Zealot

First strike, haste
Whenever a player casts a spell from a graveyard, this creature deals 3 damage to that player.

Ob Nixilis, the Hate-Twisted

Whenever an opponent draws a card, Ob Nixilis deals 1 damage to that player.
−2: Destroy target creature. Its controller draws two cards.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, this creature deals 1 damage to that creature's controller.