Cloister Gargoyle

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

Concealed Courtyard

Concealed Courtyard enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {B}.

Yuan-Ti Malison

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

Cave of the Frost Dragon

If you control two or more other lands, Cave of the Frost Dragon enters tapped.
{T}: Add {W}.
{4}{W}: Cave of the Frost Dragon becomes a 3/4 white Dragon creature with flying until end of turn. It's still a land.

Varis, Silverymoon Ranger

Reach, ward {1}
Whenever you cast a creature or planeswalker spell, 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.)
Whenever you complete a dungeon, create a 2/2 green Wolf creature token.

Forest

Precipitous Drop

Enchant creature
When Precipitous Drop 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.

Swamp

Wandering Troubadour

At the beginning of your end step, if you had a land enter the battlefield under your control this turn, venture into the dungeon. (Enter the first room or advance to the next room.)

Veteran Dungeoneer

When Veteran Dungeoneer enters, venture into the dungeon. (Enter the first room or advance to the next room.)

Triumphant Adventurer

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

Dungeon Descent

Dungeon Descent 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.)

You Find a Cursed Idol

Choose one —
• Smash It — Destroy target artifact.
• Lift the Curse — Destroy target enchantment.
• Steal Its Eyes — Create a Treasure token and venture into the dungeon. (Enter the first room or advance to the next room.)

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.)

Yuan-Ti Fang-Blade

Deathtouch
Whenever Yuan-Ti Fang-Blade deals combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Find the Path

Enchant land
When Find the Path enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Enchanted land has "{T}: Add {G}{G}."

Bar the Gate

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

Ellywick Tumblestrum

+1: Venture into the dungeon. (Enter the first room or advance to the next room.)
−2: Look at the top six cards of your library. You may reveal a creature card from among them and put it into your hand. If it's legendary, you gain 3 life. Put the rest on the bottom of your library in a random order.
−7: You get an emblem with "Creatures you control have trample and haste and get +2/+2 for each differently named dungeon you've completed."

Plains

Zalto, Fire Giant Duke

Trample
Whenever Zalto, Fire Giant Duke is dealt damage, venture into the dungeon. (Enter the first room or advance to the next room.)

Barrowin of Clan Undurr

When Barrowin of Clan Undurr enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Whenever Barrowin of Clan Undurr 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.

Intrepid Outlander

Reach
Pack tactics — Whenever Intrepid Outlander attacks, if you attacked with creatures with total power 6 or greater this combat, venture into the dungeon. (Enter the first room or advance to the next room.)

Nadaar, Selfless Paladin

Vigilance
Whenever Nadaar, Selfless Paladin 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.

Planar Ally

Flying
Whenever Planar Ally attacks, venture into the dungeon. (Enter the first room or advance to the next room.)

Delver's Torch

Equipped creature gets +1/+1.
Whenever equipped creature attacks, venture into the dungeon. (Enter the first room or advance to the next room.)
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Acererak the Archlich

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

Eccentric Apprentice

Flying
When Eccentric Apprentice enters, venture into the dungeon. (Enter the first room or advance to the next room.)
At the beginning of combat on your turn, if you've completed a dungeon, up to one target creature becomes a Bird with base power and toughness 1/1 and flying until end of turn.

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.)