Fate Unraveler

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

Dark Deal

Each player discards all the cards in their hand, then draws that many cards minus one.

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Underworld Dreams

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

Seizan, Perverter of Truth

At the beginning of each player's upkeep, that player loses 2 life and draws two cards.

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Megrim

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

Bloodchief Ascension

At the beginning of each end step, if an opponent lost 2 or more life this turn, you may put a quest counter on this enchantment. (Damage causes loss of life.)
Whenever a card is put into an opponent's graveyard from anywhere, if this enchantment has three or more quest counters on it, you may have that player lose 2 life. If you do, you gain 2 life.

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.

Liliana's Caress

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

Waste Not

Whenever an opponent discards a creature card, create a 2/2 black Zombie creature token.
Whenever an opponent discards a land card, add {B}{B}.
Whenever an opponent discards a noncreature, nonland card, draw a card.