Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Relic Bane

Enchant artifact
Enchanted artifact has "At the beginning of your upkeep, you lose 2 life."

Feast on the Fallen

At the beginning of each upkeep, if an opponent lost life last turn, put a +1/+1 counter on target creature you control.

Underworld Dreams

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

Grim Guardian

Constellation — Whenever this creature or another enchantment you control enters, each opponent loses 1 life.

Dash Hopes

When you cast this spell, any player may pay 5 life. If a player does, counter Dash Hopes.
Counter target spell.

Serrated Scorpion

When this creature dies, it deals 2 damage to each opponent and you gain 2 life.

Revenge of Ravens

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life and you gain 1 life.

Cast Down

Profane Insight

You draw a card and you lose 1 life. (Then exile this card. You may cast the creature later from exile.)

Foulmire Knight

Foulmire Knight // Profane Insight

Sign in Blood

Target player draws two cards and loses 2 life.

Swamp

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Clawing Torment

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets -1/-1 and can't block.
Enchanted permanent has "At the beginning of your upkeep, you lose 1 life."