Mist-Cloaked Herald

Champion's Helm

Equipped creature gets +2/+2.
As long as equipped creature is legendary, it has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Vicious Battlerager

When this creature enters, you take the initiative.
Spiked Retribution — Whenever this creature becomes blocked by a creature, that creature's controller loses 5 life.

Mask of Avacyn

Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip {3}

Dimir Infiltrator

This creature can't be blocked.
Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Latch Seeker

Changeling Outcast

Changeling (This card is every creature type.)
This creature can't block and can't be blocked.

Faerie Dragon

Invisible Stalker

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
This creature can't be blocked.

Triton Shorestalker

Tormented Soul

This creature can't block and can't be blocked.

Sarevok's Tome

When this artifact enters, you take the initiative.
{T}: Add {C}. If you have the initiative, add {C}{C} instead.
{3}, {T}: Exile cards from the top of your library until you exile a nonland card. You may cast that card without paying its mana cost. Activate only if you've completed a dungeon.

Escape Artist

This creature can't be blocked.
{U}, Discard a card: Return this creature to its owner's hand.

Flitterstep Eidolon

Bestow {5}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
This creature can't be blocked.
Enchanted creature gets +1/+1 and can't be blocked.

Giant's Amulet

When this Equipment enters, you may pay {3}{U}. If you do, create a 4/4 blue Giant Wizard creature token, then attach this Equipment to it.
Equipped creature gets +0/+1 and has "This creature has hexproof as long as it's untapped."(It can't be the target of spells or abilities your opponents control.)
Equip {2}

The Initiative

Whenever one or more creatures a player controls deal combat damage to you, that player takes the initiative.
Whenever you take the initiative and at the beginning of your upkeep, venture into Undercity. (If you're in a dungeon, advance to the next room. If you're not, enter Undercity. You can take the initiative even if you already have it.)

Undercity

You can't enter this dungeon unless you "venture into Undercity."
Secret Entrance — Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Leads to: Forge, Lost Well)
Forge — Put two +1/+1 counters on target creature. (Leads to: Trap!, Arena)
Lost Well — Scry 2. (Leads to: Arena, Stash)
Trap! — Target player loses 5 life. (Leads to: Archives)
Arena — Goad target creature. (Leads to: Archives, Catacombs)
Stash — Create a Treasure token. (Leads to: Catacombs)
Archives — Draw a card. (Leads to: Throne of the Dead Three)
Catacombs — Create a 4/1 black Skeleton creature token with menace. (Leads to: Throne of the Dead Three)
Throne of the Dead Three — Reveal the top ten cards of your library. Put a creature card from among them onto the battlefield with three +1/+1 counters on it. It gains hexproof until your next turn. Then shuffle.

Undercity // The Initiative

Gray Harbor Merfolk

This creature can't be blocked.
This creature gets +2/+0 as long as you control a commander that's a creature or planeswalker.

Rilsa Rael, Kingpin

Deathtouch
When Rilsa Rael enters, you take the initiative.
Whenever you attack, target attacking creature gains deathtouch until end of turn. If you've completed a dungeon, that creature also gets +5/+0 and gains first strike and menace until end of turn.

Aarakocra Sneak

Flying
When this creature enters, you take the initiative.

Skeleton

Menace (This creature can't be blocked except by two or more creatures.)

Vedalken Infiltrator

This creature can't be blocked.
Metalcraft — This creature gets +1/+0 as long as you control three or more artifacts.

Gudul Lurker

This creature can't be blocked.
Megamorph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)

Mirror Shield

Equipped creature gets +0/+2 and has hexproof and "Whenever a creature with deathtouch blocks or becomes blocked by this creature, destroy that creature."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Imoen, Mystic Trickster

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
At the beginning of your end step, if you have the initiative, draw a card. Draw another card if you've completed a dungeon.
Choose a Background (You can have a Background as a second commander.)

Slither Blade

Tomb of Horrors Adventurer

When this creature enters, you take the initiative.
Whenever you cast your second spell each turn, copy it. If you've completed a dungeon, copy that spell twice instead. You may choose new targets for the copies. (A copy of a permanent spell becomes a token.)

Cephalid Facetaker

This creature can't be blocked.
At the beginning of combat on your turn, you may have this creature become a copy of another target creature until end of turn, except it's 1/4 and has "This creature can't be blocked."

Feywild Caretaker

When this creature enters, you take the initiative.
At the beginning of your end step, if you have the initiative, create a 1/1 blue Faerie Dragon creature token with flying.

Underdark Explorer

Menace (This creature can't be blocked except by two or more creatures.)
When this creature enters, you take the initiative.

From the Catacombs

Put target creature card from a graveyard onto the battlefield under your control with a corpse counter on it. You take the initiative. If that creature would leave the battlefield, exile it instead of putting it anywhere else.
Escape—{3}{B}{B}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Ravenloft Adventurer

When this creature enters, you take the initiative.
If a creature an opponent controls would die, instead exile it and put a hit counter on it.
Whenever this creature attacks, if you've completed a dungeon, defending player loses 1 life for each card they own in exile with a hit counter on it.

Dungeon Delver

Commander creatures you own have "Room abilities of dungeons you own trigger an additional time."

River Sneak

This creature can't be blocked.
Whenever another Merfolk you control enters, this creature gets +1/+1 until end of turn.

Dungeoneer's Pack

This artifact enters tapped.
{2}, {T}, Sacrifice this artifact: You take the initiative, gain 3 life, draw a card, and create a Treasure token. Activate only as a sorcery. (A Treasure token is an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Safana, Calimport Cutthroat

Menace
At the beginning of your end step, if you have the initiative, create a Treasure token. Create three of those tokens instead if you've completed a dungeon.
Choose a Background (You can have a Background as a second commander.)

Benthic Infiltrator

Devoid (This card has no color.)
Ingest (Whenever this creature deals combat damage to a player, that player exiles the top card of their library.)
This creature can't be blocked.

Metathran Soldier

Passageway Seer

Lifelink
When this creature enters, you take the initiative.
At the beginning of your end step, if you have the initiative, put a +1/+1 counter on this creature.

Inkfathom Infiltrator

Mercurial Spelldancer

This creature can't be blocked.
Whenever you cast a noncreature spell, put an oil counter on this creature.
Whenever this creature deals combat damage to a player, you may remove two oil counters from it. If you do, when you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Treasure

{T}, Sacrifice this token: Add one mana of any color.

Trailblazer's Torch

When this Equipment enters, you take the initiative.
Whenever equipped creature becomes blocked, it deals 2 damage to each creature blocking it.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Aether Figment

Kicker {3} (You may pay an additional {3} as you cast this spell.)
If this creature was kicked, it enters with two +1/+1 counters on it.
This creature can't be blocked.

Robe of Mirrors

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature has shroud. (It can't be the target of spells or abilities.)