Thorough Investigation

Whenever you attack, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, venture into the dungeon. (Enter the first room or advance to the next room.)

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Ranger's Hawk

Flying
{3}, {T}, Tap another untapped creature you control: Venture into the dungeon. Activate only as a sorcery. (Enter the first room or advance to the next room.)

Shattered Sanctum

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {B}.

Despark

Exile target permanent with mana value 4 or greater.

Dungeon Delver

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

Swamp

Displacer Beast

When this creature enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Displacement — {3}{U}: Return this creature to its owner's hand.

Yuan-Ti Malison

This creature can't be blocked as long as it's attacking alone.
Whenever this creature deals combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Sea of Clouds

This land enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Deserted Beach

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Precipitous Drop

Enchant creature
When this Aura enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Enchanted creature gets -2/-2. It gets -5/-5 instead as long as you've completed a dungeon.

Drowned Catacomb

This land enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Clattering Skeletons

When this creature dies, venture into the dungeon. (Enter the first room or advance to the next room.)

Supreme Verdict

This spell can't be countered.
Destroy all creatures.

Island

Secret Door

Defender
{4}{U}: Venture into the dungeon. Activate only as a sorcery. (Enter the first room or advance to the next room.)

Prairie Stream

({T}: Add {W} or {U}.)
This land enters tapped unless you control two or more basic lands.

Cloister Gargoyle

When this creature enters, venture into the dungeon. (Enter the first room or advance to the next room.)
As long as you've completed a dungeon, this creature gets +3/+0 and has flying.

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.)

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Counterspell

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Dungeon Descent

This land enters tapped.
{T}: Add {C}.
{4}, {T}, Tap an untapped legendary creature you control: Venture into the dungeon. Activate only as a sorcery. (Enter the first room or advance to the next room.)

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Dimir Signet

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Midnight Pathlighter

Creatures you control can't be blocked except by legendary creatures.
Whenever one or more creatures you control deal combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Sol Ring

Void Rend

This spell can't be countered.
Destroy target nonland permanent.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

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.

Fellwar Stone

Animate Dead

Enchant creature card in a graveyard
When this Aura enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with this Aura." Return enchanted creature card to the battlefield under your control and attach this Aura to it. When this Aura leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

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.

Baleful Strix

Flying, deathtouch
When this creature enters, draw a card.

Dimir Aqueduct

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Talisman of Hierarchy

{T}: Add {C}.
{T}: Add {W} or {B}. This artifact deals 1 damage to you.

Immovable Rod

You may choose not to untap this artifact during your untap step.
Whenever this artifact becomes untapped, venture into the dungeon.
{3}{W}, {T}: For as long as this artifact remains tapped, another target permanent loses all abilities and can't attack or block.

Obscura Storefront

When this land enters, sacrifice it. When you do, search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Orzhov Basilica

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{B}.

Isolated Chapel

This land enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

Victimize

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Enchant creature
Enchanted creature has flying and "Whenever this creature deals combat damage to a player, venture into the dungeon." (Enter the first room or advance to the next room.)

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

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.)

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Evolving Wilds

Fates' Reversal

Return up to one target creature card from your graveyard to your hand. Venture into the dungeon. (Enter the first room or advance to the next room.)

Morphic Pool

This land enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Azorius Signet

Triumphant Adventurer

Deathtouch
During your turn, this creature has first strike.
Whenever this creature attacks, venture into the dungeon. (Enter the first room or advance to the next room.)

White Plume Adventurer

When this creature enters, you take the initiative.
At the beginning of each opponent's upkeep, untap a creature you control. If you've completed a dungeon, untap all creatures you control instead.

Bar the Gate

Counter target creature or planeswalker spell. Venture into the dungeon. (Enter the first room or advance to the next room.)

Barrowin of Clan Undurr

When Barrowin enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Whenever Barrowin attacks, return up to one creature card with mana value 3 or less from your graveyard to the battlefield if you've completed a dungeon.

Acererak the Archlich

When Acererak enters, if you haven't completed Tomb of Annihilation, return Acererak to its owner's hand and venture into the dungeon.
Whenever Acererak attacks, for each opponent, you create a 2/2 black Zombie creature token unless that player sacrifices a creature of their choice.

Arcane Sanctum

This land enters tapped.
{T}: Add {W}, {U}, or {B}.

Orzhov Signet

Hama Pashar, Ruin Seeker

Room abilities of dungeons you own trigger an additional time.

Azorius Chancery

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Unburial Rites

Return target creature card from your graveyard to the battlefield.
Flashback {3}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Vault of Champions

This land enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.

Contaminated Landscape

{T}: Add {C}.
{T}, Sacrifice this land: Search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle.
Cycling {W}{U}{B} ({W}{U}{B}, Discard this card: Draw a card.)

Plains

Sunken Hollow

({T}: Add {U} or {B}.)
This land enters tapped unless you control two or more basic lands.

Command Tower

Sefris of the Hidden Ways

Whenever one or more creature cards are put into your graveyard from anywhere, venture into the dungeon. This ability triggers only once each turn. (To venture into the dungeon, enter the first room or advance to the next room.)
Create Undead — Whenever you complete a dungeon, return target creature card from your graveyard to the battlefield.

Shipwreck Marsh

This land enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

Nadaar, Selfless Paladin

Vigilance
Whenever Nadaar enters or attacks, venture into the dungeon. (Enter the first room or advance to the next room.)
Other creatures you control get +1/+1 as long as you've completed a dungeon.

Dungeon Map

{T}: Add {C}.
{3}, {T}: Venture into the dungeon. Activate only as a sorcery. (Enter the first room or advance to the next room.)

Glacial Fortress

This land enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Yuan-Ti Fang-Blade

Deathtouch
Whenever this creature deals combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Radiant Solar

Flying, lifelink
Whenever this creature or another nontoken creature you control enters, venture into the dungeon. (Enter the first room or advance to the next room.)
{W}, Discard this card: Venture into the dungeon and you gain 3 life.