Thraximundar

Haste
Whenever Thraximundar attacks, defending player sacrifices a creature.
Whenever a player sacrifices a creature, you may put a +1/+1 counter on Thraximundar.

Agent of the Fates

Deathtouch
Heroic — Whenever you cast a spell that targets Agent of the Fates, each opponent sacrifices a creature.

Etrata, the Silencer

Etrata, the Silencer can't be blocked.
Whenever Etrata deals combat damage to a player, exile target creature that player controls and put a hit counter on that card. That player loses the game if they own three or more exiled cards with hit counters on them. Etrata's owner shuffles Etrata into their library.

Goblin Assassin

Whenever Goblin Assassin or another Goblin enters, each player flips a coin. Each player whose coin comes up tails sacrifices a creature.