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, the Grim 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.)

Veinwitch Coven

Menace
Whenever you gain life, you may pay {B}. If you do, return target creature card from your graveyard to your hand.

Astarion, the Decadent

Deathtouch, lifelink
At the beginning of your end step, choose one —
• Feed — Target opponent loses life equal to the amount of life they lost this turn.
• Friends — You gain life equal to the amount of life you gained this turn.

Have

Murder

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Pact Weapon

As long as Pact Weapon is attached to a creature, you don't lose the game for having 0 or less life.
Whenever equipped creature attacks, draw a card and reveal it. The creature gets +X/+X until end of turn and you lose X life, where X is that card's mana value.
Equip—Discard a card.

Duress

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

Suffer the Past

Exile X target cards from target player's graveyard. For each card exiled this way, that player loses 1 life and you gain 1 life.

K'rrik, Son of Yawgmoth

({B/P} can be paid with either {B} or 2 life.)
Lifelink
For each {B} in a cost, you may pay 2 life rather than pay that mana.
Whenever you cast a black spell, put a +1/+1 counter on K'rrik, Son of Yawgmoth.

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Baldur's Gate

{T}: Add {C}.
{2}, {T}: Add X mana of any one color, where X is the number of other Gates you control.

Sorin, Vengeful Bloodlord

During your turn, creatures and planeswalkers you control have lifelink.
+2: Sorin, Vengeful Bloodlord deals 1 damage to target player or planeswalker.
−X: Return target creature card with mana value X from your graveyard to the battlefield. That creature is a Vampire in addition to its other types.

Victim of Night

Destroy target non-Vampire, non-Werewolf, non-Zombie creature.

Hold the Gates

Creatures you control get +0/+1 for each Gate you control and have vigilance.

Astarion's Thirst

Exile target creature. Put X +1/+1 counters on a commander creature you control, where X is the power of the creature exiled this way.