Rug of Smothering

Flying
Whenever a player casts a spell, they lose 1 life for each spell they've cast this turn.

Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Mayhem Devil

Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target.

Korvold, Fae-Cursed King

Flying
Whenever Korvold, Fae-Cursed King enters or attacks, sacrifice another permanent.
Whenever you sacrifice a permanent, put a +1/+1 counter on Korvold and draw a card.

Inspired Tinkering

Exile the top three cards of your library. Until the end of your next turn, you may play those cards.
Create three Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Phyrexian Arena

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

Woodland Cemetery

Woodland Cemetery enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni, Undying Partisan.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Tibalt, Cosmic Impostor

As Tibalt enters, you get an emblem with "You may play cards exiled with Tibalt, Cosmic Impostor, and you may spend mana as though it were mana of any color to cast those spells."
+2: Exile the top card of each player's library.
−3: Exile target artifact or creature.
−8: Exile all graveyards. Add {R}{R}{R}.

Valki, God of Lies

When Valki enters, each opponent reveals their hand. For each opponent, exile a creature card they revealed this way until Valki leaves the battlefield.
{X}: Choose a creature card exiled with Valki with mana value X. Valki becomes a copy of that card.

Valki, God of Lies // Tibalt, Cosmic Impostor

Cindervines

Whenever an opponent casts a noncreature spell, Cindervines deals 1 damage to that player.
{1}, Sacrifice Cindervines: Destroy target artifact or enchantment. Cindervines deals 2 damage to that permanent's controller.

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.

Assassin's Trophy

Destroy target permanent an opponent controls. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Dreadbore

Cinder Glade

({T}: Add {R} or {G}.)
Cinder Glade enters tapped unless you control two or more basic lands.