Volo, Itinerant Scholar

When Volo enters, create Volo's Journal, a legendary colorless artifact token with hexproof and "Whenever you cast a creature spell, note one of its creature types that hasn't been noted for this artifact."
{2}, {T}: Draw a card for each creature type noted for target permanent you control named Volo's Journal.
Choose a Background

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

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.)

Ghostly Changeling

Changeling (This card is every creature type.)
{1}{B}: Ghostly Changeling gets +1/+1 until end of turn.

Littjara Kinseekers

Changeling (This card is every creature type.)
When Littjara Kinseekers enters, if you control three or more creatures that share a creature type, put a +1/+1 counter on Littjara Kinseekers, then scry 1.

Cairn Wanderer

Changeling (This card is every creature type.)
As long as a creature card with flying is in a graveyard, Cairn Wanderer has flying. The same is true for fear, first strike, double strike, deathtouch, haste, landwalk, lifelink, protection, reach, trample, shroud, and vigilance.

Ashnod's Altar

Graveshifter

Changeling (This card is every creature type.)
When Graveshifter enters, you may return target creature card from your graveyard to your hand.

Reflections of Littjara

As Reflections of Littjara enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Bloodline Pretender

Changeling (This card is every creature type.)
As Bloodline Pretender enters, choose a creature type.
Whenever another creature you control of the chosen type enters, put a +1/+1 counter on Bloodline Pretender.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Retribution of the Ancients

{B}, Remove X +1/+1 counters from among creatures you control: Target creature gets -X/-X until end of turn.

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Three Tree Mascot

Changeling (This card is every creature type.)
{1}: Add one mana of any color. Activate only once each turn.

Moonglove Changeling

Changeling (This card is every creature type.)
{B}: Moonglove Changeling gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy that creature.)

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Venomous Changeling

Changeling (This card is every creature type.)
Deathtouch

Lord of the Unreal

Illusion creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Mistwalker

Changeling (This card is every creature type.)
Flying
{1}{U}: Mistwalker gets +1/-1 until end of turn.

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Universal Automaton

Changeling (This card is every creature type.)

Skeletal Changeling

Changeling (This card is every creature type.)
{1}{B}: Regenerate Skeletal Changeling.

Viscera Seer

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

Burakos, Party Leader

Burakos, Party Leader is also a Cleric, Rogue, Warrior, and Wizard.
Whenever Burakos attacks, defending player loses X life and you create X Treasure tokens, where X is the number of creatures in your party.
Choose a Background (You can have a Background as a second commander.)

Barkform Harvester

Changeling (This card is every creature type.)
Reach
{2}: Put target card from your graveyard on the bottom of your library.