Quest for the Nihil Stone

Whenever an opponent discards a card, you may put a quest counter on Quest for the Nihil Stone.
At the beginning of each opponent's upkeep, if that player has no cards in hand and Quest for the Nihil Stone has two or more quest counters on it, you may have that player lose 5 life.

Nyxathid

As Nyxathid enters, choose an opponent.
Nyxathid gets -1/-1 for each card in the chosen player's hand.

Mountain

Shimian Specter

Flying
Whenever Shimian Specter deals combat damage to a player, that player reveals their hand. You choose a nonland card from it. Search that player's graveyard, hand, and library for all cards with the same name as that card and exile them. Then that player shuffles.

Blightning

Blightning deals 3 damage to target player or planeswalker. That player or that planeswalker's controller discards two cards.

Virus Beetle

When Virus Beetle enters, each opponent discards a card.

Liliana's Caress

Whenever an opponent discards a card, that player loses 2 life.

Hypnotic Specter

Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.

Hymn to Tourach

Target player discards two cards at random.

Tainted Peak

{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.

Burning Inquiry

Each player draws three cards, then discards three cards at random.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Ostracize

Target opponent reveals their hand. You choose a creature card from it. That player discards that card.

Cremate

Exile target card from a graveyard.
Draw a card.

Shadowfeed

Exile target card from a graveyard. You gain 3 life.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Dark Ritual

Terminate

Destroy target creature. It can't be regenerated.