Valgavoth, Harrower of Souls

Flying
Ward—Pay 2 life.
Whenever an opponent loses life for the first time during each of their turns, put a +1/+1 counter on Valgavoth and draw a card.

Rakdos Signet

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.

Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Infernal Grasp

Destroy target creature. You lose 2 life.

Manabarbs

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

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

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.

Toxic Deluge

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

Razorkin Needlehead

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

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Zo-Zu the Punisher

Whenever a land enters, Zo-Zu deals 2 damage to that land's controller.

Solphim, Mayhem Dominus

If a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals double that damage to that player or permanent instead.
{1}{R/P}{R/P}, Discard two cards: Put an indestructible counter on Solphim. ({R/P} can be paid with either {R} or 2 life.)

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. This artifact deals 1 damage to you.

Brash Taunter

Indestructible
Whenever this creature is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: This creature fights another target creature.

Fate Unraveler

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

Valgavoth's Lair

Hexproof
This land enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.

Unstoppable Slasher

Deathtouch
Whenever this creature deals combat damage to a player, they lose half their life, rounded up.
When this creature dies, if it had no counters on it, return it to the battlefield tapped under its owner's control with two stun counters on it.

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.

Underworld Dreams

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

Mountain

Foreboding Ruins

As this land enters, you may reveal a Swamp or Mountain card from your hand. If you don't, this land enters tapped.
{T}: Add {B} or {R}.