Seedborn Muse

Untap all permanents you control during each other player's untap step.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if there are seven or more cards in your graveyard.

Haunted One

Commander creatures you own have "Whenever this creature becomes tapped, it and other creatures you control that share a creature type with it each get +2/+0 and gain undying until end of turn." (When a creature with undying 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.)

Abby, Merciless Soldier

When you cast this spell, create a number of 1/1 black Fungus Zombie creature tokens named Cordyceps Infected equal to the amount of mana spent to cast it.
Abby enters under the control of an opponent of your choice.
Partner—Survivors (You can have two commanders if both have this ability.)

Hansk, Slayer Zealot

At the beginning of your upkeep, target opponent creates three Walker tokens. (They're 2/2 black Zombie creatures.)
{T}: Hansk, Slayer Zealot deals 2 damage to target creature.
Whenever a Zombie an opponent controls dies, draw a card.

The Mycotyrant

Trample
The Mycotyrant's power and toughness are each equal to the number of creatures you control that are Fungi and/or Saprolings.
At the beginning of your end step, create X 1/1 black Fungus creature tokens with "This token can't block," where X is the number of times you descended this turn. (You descend each time a permanent card is put into your graveyard from anywhere.)

Krenko, Mob Boss

{T}: Create X 1/1 red Goblin creature tokens, where X is the number of Goblins you control.

Joel, Resolute Survivor

Menace
Whenever a creature token dies, put a +1/+1 counter on Joel and draw a card. This ability triggers only once each turn.
Partner—Survivors (You can have two commanders if both have this ability.)

Carrion Feeder

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

Korvold, Fae-Cursed King

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

Ellie, Brick Master

Distract the Horde — Whenever a player attacks one of your opponents, that attacking player creates a tapped 1/1 black Fungus Zombie creature token named Cordyceps Infected that's attacking that opponent.
Partner—Survivors (You can have two commanders if both have this ability.)

Enkira, Hostile Scavenger

When Enkira, Hostile Scavenger enters, create two Walker tokens. (They're 2/2 black Zombie creatures.)
As long as Enkira is equipped, it must be blocked if able.
Whenever Enkira and at least two Zombies attack, Enkira gains indestructible until end of turn.

Mycoloth

Devour 2 (As this creature enters, you may sacrifice any number of creatures. It enters with twice that many +1/+1 counters on it.)
At the beginning of your upkeep, create a 1/1 green Saproling creature token for each +1/+1 counter on this creature.

Melira, Sylvok Outcast

You can't get poison counters.
Creatures you control can't have -1/-1 counters put on them.
Creatures your opponents control lose infect.

Ellie, Vengeful Hunter

Pay 2 life, Sacrifice another creature: Ellie deals 2 damage to target player and gains indestructible until end of turn.
Partner—Survivors (You can have two commanders if both have this ability.)

Dictate of Erebos

Flash
Whenever a creature you control dies, each opponent sacrifices a creature of their choice.

Thornbite Staff

Equipped creature has "{2}, {T}: This creature deals 1 damage to any target" and "Whenever a creature dies, untap this creature."
Whenever a Shaman creature enters, you may attach this Equipment to it.
Equip {4}

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.