Soot Imp

Flying
Whenever a player casts a nonblack spell, that player loses 1 life.

Rug of Smothering

Flying
Whenever a player casts a spell, they lose 1 life for each spell they've cast this turn.

Liesa, Shroud of Dusk

Rather than pay {2} for each previous time you've cast this spell from the command zone this game, pay 2 life that many times.
Flying, lifelink
Whenever a player casts a spell, they lose 2 life.

Curse of Wizardry

As this enchantment enters, choose a color.
Whenever a player casts a spell of the chosen color, that player loses 1 life.

Painful Quandary

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

Kambal, Consul of Allocation

Whenever an opponent casts a noncreature spell, that player loses 2 life and you gain 2 life.