The Darkness Crystal

Black spells you cast cost {1} less to cast.
If a nontoken creature an opponent controls would die, instead exile it and you gain 2 life.
{4}{B}{B}, {T}: Put target creature card exiled with The Darkness Crystal onto the battlefield tapped under your control with two additional +1/+1 counters on it.

Leyline of the Void

If this card is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

Ketramose, the New Dawn

Menace, lifelink, indestructible
Ketramose can't attack or block unless there are seven or more cards in exile.
Whenever one or more cards are put into exile from graveyards and/or the battlefield during your turn, you draw a card and lose 1 life.

Syr Vondam, Sunstar Exemplar

Vigilance, menace
Whenever another creature you control dies or is put into exile, put a +1/+1 counter on Syr Vondam and you gain 1 life.
When Syr Vondam dies or is put into exile while its power is 4 or greater, destroy up to one target nonland permanent.