Cavalier of Night

Lifelink
When Cavalier of Night enters, you may sacrifice another creature. When you do, destroy target creature an opponent controls.
When Cavalier of Night dies, return target creature card with mana value 3 or less from your graveyard to the battlefield.

Because I Have Willed It

(An ongoing scheme remains face up until it's abandoned.)
Spells you cast cost {1} less to cast.
At the beginning of your opponents' end step, if they cast four or more spells this turn, abandon this scheme.

Agate-Blade Assassin

Whenever Agate-Blade Assassin attacks, defending player loses 1 life and you gain 1 life.

Blood Funnel

Noncreature spells you cast cost {2} less to cast.
Whenever you cast a noncreature spell, counter that spell unless you sacrifice a creature.

Acolyte of Aclazotz

{T}, Sacrifice another creature or artifact: Each opponent loses 1 life and you gain 1 life.

Profane Transfusion

Two target players exchange life totals. You create an X/X colorless Horror artifact creature token, where X is the difference between those players' life totals.

Gallowbraid

Trample
Cumulative upkeep—Pay 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Cateran Overlord

Sacrifice a creature: Regenerate Cateran Overlord.
{6}, {T}: Search your library for a Mercenary permanent card with mana value 6 or less, put it onto the battlefield, then shuffle.

Morinfen

Flying
Cumulative upkeep—Pay 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)