Have (in decks)

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Don't Have

Agent Venom

Flash
Menace
Whenever another nontoken creature you control dies, you draw a card and lose 1 life.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Proxy

Bitterbloom Bearer

Flash
Flying
At the beginning of your upkeep, you lose 1 life and create a 1/1 blue and black Faerie creature token with flying.

Emptiness

When this creature enters, if {W}{W} was spent to cast it, return target creature card with mana value 3 or less from your graveyard to the battlefield.
When this creature enters, if {B}{B} was spent to cast it, put three -1/-1 counters on up to one target creature.
Evoke {W/B}{W/B}

Morningtide's Light

Exile any number of target creatures. At the beginning of the next end step, return those cards to the battlefield tapped under their owners' control.
Until your next turn, prevent all damage that would be dealt to you.
Exile Morningtide's Light.

Carrion Feeder

This creature can't block.
Sacrifice a creature: Put a +1/+1 counter on this creature.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Have

The Soul Stone

Indestructible
{T}: Add {B}.
{6}{B}, {T}, Exile a creature you control: Harness The Soul Stone. (Once harnessed, its ∞ ability is active.)
∞ — At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.

Isilu, Carrier of Twilight

Flying, lifelink
Each other nontoken creature you control has persist. (When it dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
At the beginning of your first main phase, you may pay {W}. If you do, transform Isilu.

Eirdu, Carrier of Dawn

Flying, lifelink
Creature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a creature spell pays for {1} or one mana of that creature's color.)
At the beginning of your first main phase, you may pay {B}. If you do, transform Eirdu.

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Ashnod's Altar

Zulaport Cutthroat

Whenever this creature or another creature you control dies, each opponent loses 1 life and you gain 1 life.