Kresh the Bloodbraided

Whenever another creature dies, you may put X +1/+1 counters on Kresh the Bloodbraided, where X is that creature's power.

Sek'Kuar, Deathkeeper

Whenever another nontoken creature you control dies, create a 3/1 black and red Graveborn creature token with haste.

Korvold, Fae-Cursed King

Flying
Whenever Korvold, Fae-Cursed King enters or attacks, sacrifice another permanent.
Whenever you sacrifice a permanent, put a +1/+1 counter on Korvold and draw a card.