Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Sol Ring

Fraying Omnipotence

Each player loses half their life, then discards half the cards in their hand, then sacrifices half the creatures they control of their choice. Round up each time.

Innocent Blood

Each player sacrifices a creature of their choice.

Elderfang Disciple

When Elderfang Disciple enters, each opponent discards a card.

Arcane Signet

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

Gravelighter

Flying
When Gravelighter enters, draw a card if a creature died this turn. Otherwise, each player sacrifices a creature of their choice.

Braids, Arisen Nightmare

At the beginning of your end step, you may sacrifice an artifact, creature, enchantment, land, or planeswalker. If you do, each opponent may sacrifice a permanent of their choice that shares a card type with it. For each opponent who doesn't, that player loses 2 life and you draw a card.

Demon of Loathing

Flying, trample
Whenever Demon of Loathing deals combat damage to a player, that player sacrifices a creature of their choice.

Eradicator Valkyrie

Flying, lifelink, hexproof from planeswalkers
Boast — {1}{B}, Sacrifice a creature: Each opponent sacrifices a creature or planeswalker. (Activate only if this creature attacked this turn and only once each turn.)

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Tergrid's Shadow

Each player sacrifices two creatures.
Foretell {2}{B}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Virus Beetle

When Virus Beetle enters, each opponent discards a card.

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Swamp

Tergrid's Lantern

{T}: Target player loses 3 life unless they sacrifice a nonland permanent of their choice or discard a card.
{3}{B}: Untap Tergrid's Lantern.

Tergrid, God of Fright

Menace
Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control.