Crow of Dark Tidings

Flying
When this creature enters or dies, mill two cards. (Put the top two cards of your library into your graveyard.)

Orzhov Signet

Necromancer's Assistant

When Necromancer's Assistant enters, mill three cards.

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.)

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Leaden Myr

Plains

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.

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.)

Funeral Rites

You draw two cards, lose 2 life, then mill two cards.

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.

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.)

Oubliette

When Oubliette enters, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Asha's Favor

Enchant creature
Enchanted creature has flying, first strike, and vigilance.

Gold Myr

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Swamp

Veteran Dungeoneer

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

Stinkweed Imp

Flying
Whenever Stinkweed Imp deals combat damage to a creature, destroy that creature.
Dredge 5 (If you would draw a card, you may mill five cards instead. If you do, return this card from your graveyard to your hand.)

Eye Collector

Flying
Whenever Eye Collector deals combat damage to a player, each player mills a card. (Each player puts the top card of their library into their graveyard.)

Griffin Sentinel

Flying
Vigilance (Attacking doesn't cause this creature to tap.)

Clattering Skeletons

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

Arcane Signet

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

Planar Ally

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

Strixhaven Stadium

{T}: Add {C}. Put a point counter on Strixhaven Stadium.
Whenever a creature deals combat damage to you, remove a point counter from Strixhaven Stadium.
Whenever a creature you control deals combat damage to an opponent, put a point counter on Strixhaven Stadium. Then if it has ten or more point counters on it, remove them all and that player loses the game.

Viscera Seer

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

Zombie Ogre

At the beginning of your end step, if a creature died this turn, venture into the dungeon. (Enter the first room or advance to the next room.)