Ulcerate

Target creature gets -3/-3 until end of turn. You lose 3 life.

Howling Banshee

Flying
When this creature enters, each player loses 3 life.

Scourge of the Undercity

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When this creature enters, another target creature you control gains lifelink until end of turn.

Metalspinner's Puzzleknot

When this artifact enters, you draw a card and you lose 1 life.
{2}{B}, Sacrifice this artifact: You draw a card and you lose 1 life.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Vilis, Broker of Blood

Flying
{B}, Pay 2 life: Target creature gets -1/-1 until end of turn.
Whenever you lose life, draw that many cards. (Damage causes loss of life.)

Infernal Grasp

Destroy target creature. You lose 2 life.

Alchemist's Gift

Target creature gets +1/+1 and gains your choice of deathtouch or lifelink until end of turn. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it. Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Swamp

Audacious Thief

Whenever this creature attacks, you draw a card and you lose 1 life.

Vampire Scrivener

Flying
Whenever you gain life during your turn, put a +1/+1 counter on this creature.
Whenever you lose life during your turn, put a +1/+1 counter on this creature.

Arrogant Outlaw

When this creature enters, if an opponent lost life this turn, each opponent loses 2 life and you gain 2 life.

Thriving Moor

This land enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

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.