Vish Kal, Blood Arbiter

Flying, lifelink
Sacrifice a creature: Put X +1/+1 counters on Vish Kal, Blood Arbiter, where X is the sacrificed creature's power.
Remove all +1/+1 counters from Vish Kal: Target creature gets -1/-1 until end of turn for each +1/+1 counter removed this way.

Krav, the Unredeemed

Partner with Regna, the Redeemer (When this creature enters, target player may put Regna into their hand from their library, then shuffle.)
{B}, Sacrifice X creatures: Target player draws X cards and gains X life. Put X +1/+1 counters on Krav, the Unredeemed.

Felisa, Fang of Silverquill

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever a nontoken creature you control dies, if it had counters on it, create X tapped 2/1 white and black Inkling creature tokens with flying, where X is the number of counters it had on it.

Embrose, Dean of Shadow

{T}: Put a +1/+1 counter on another target creature, then Embrose, Dean of Shadow deals 2 damage to that creature.
Whenever a creature you control with a +1/+1 counter on it dies, draw a card.

Shaile, Dean of Radiance

Flying, vigilance
{T}: Put a +1/+1 counter on each creature that entered the battlefield under your control this turn.

Shaile, Dean of Radiance // Embrose, Dean of Shadow

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Cruel Celebrant

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

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni, Undying Partisan.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Elenda, the Dusk Rose

Lifelink
Whenever another creature dies, put a +1/+1 counter on Elenda, the Dusk Rose.
When Elenda dies, create X 1/1 white Vampire creature tokens with lifelink, where X is Elenda's power.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Zulaport Cutthroat

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

Thalisse, Reverent Medium

At the beginning of each end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of tokens you created this turn.