Unquestioned Authority

Enchant creature
When Unquestioned Authority enters the battlefield, draw a card.
Enchanted creature has protection from creatures.

Gideon's Lawkeeper

Shoal Kraken

Constellation — Whenever an enchantment enters the battlefield under your control, you may draw a card. If you do, discard a card.

Weathered Sentinels

Defender, vigilance, reach, trample
Weathered Sentinels can attack players who attacked you during their last turn as though it didn't have defender.
Whenever Weathered Sentinels attacks, it gets +3/+3 and gains indestructible until end of turn.

Staunch Throneguard

Vigilance
When Staunch Throneguard enters the battlefield, you become the monarch.

Crystacean

Walking Bulwark

Defender
{2}: Until end of turn, target creature with defender gains haste, can attack as though it didn't have defender, and assigns combat damage equal to its toughness rather than its power. Activate only as a sorcery.

Mordenkainen's Polymorph

Until end of turn, target creature becomes a Dragon with base power and toughness 4/4 and gains flying. (It loses all other creature types.)

Furtive Analyst

Vigilance
{2}, {T}: Draw a card, then discard a card.

Aarakocra Sneak

Flying
When Aarakocra Sneak enters the battlefield, you take the initiative.

Escape from Orthanc

Target creature gets +1/+3 and gains flying until end of turn. Untap it.

Windborn Muse

Flying
Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

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.)

Azorius Knight-Arbiter

Vigilance
Azorius Knight-Arbiter can't be blocked.

Plains

Mesa Enchantress

Whenever you cast an enchantment spell, you may draw a card.

Righteousness

Target blocking creature gets +7/+7 until end of turn.

Tranquil Cove

Tranquil Cove enters the battlefield tapped.
When Tranquil Cove enters the battlefield, you gain 1 life.
{T}: Add {W} or {U}.

Tomb of Horrors Adventurer

When Tomb of Horrors Adventurer enters the battlefield, 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.)

Rasaad yn Bashir

Each creature you control assigns combat damage equal to its toughness rather than its power.
Whenever Rasaad yn Bashir attacks, if you have the initiative, double the toughness of each creature you control until end of turn.
Choose a Background (You can have a Background as a second commander.)

Baldin, Century Herdmaster

As long as it's your turn, each creature assigns combat damage equal to its toughness rather than its power.
Whenever Baldin, Century Herdmaster attacks, up to one hundred target creatures each get +0/+X until end of turn, where X is the number of cards in your hand.

Secret Door

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

Weakstone's Subjugation

Enchant artifact or creature
When Weakstone's Subjugation enters the battlefield, you may pay {3}. If you do, tap enchanted permanent.
Enchanted permanent doesn't untap during its controller's untap step.

Zetalpa, Primal Dawn

Flying, double strike, vigilance, trample, indestructible

Goliath Paladin

Vigilance
When Goliath Paladin enters the battlefield, you take the initiative.

Skybridge Towers

Skybridge Towers enters the battlefield tapped.
{T}: Add {W} or {U}.
{2}{W}{U}, {T}, Sacrifice Skybridge Towers: Draw a card.

Shield-Wall Sentinel

Defender
When Shield-Wall Sentinel enters the battlefield, you may search your library for a creature card with defender, reveal it, put it into your hand, then shuffle.

Refuse to Yield

Target creature gets +2/+7 until end of turn. Untap it.

Sarevok's Tome

When Sarevok's Tome enters the battlefield, 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.

Island

Thriving Heath

Thriving Heath enters the battlefield tapped.
As Thriving Heath enters the battlefield, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Giant Ox

Giant Ox crews Vehicles using its toughness rather than its power.

Citizen's Arrest

When Citizen's Arrest enters the battlefield, exile target creature or planeswalker an opponent controls until Citizen's Arrest leaves the battlefield.

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.)

Sewer Crocodile

{3}{U}: Sewer Crocodile can't be blocked this turn. This ability costs {3} less to activate if there are five or more mana values among cards in your graveyard.

Academy Wall

Defender
Whenever you cast an instant or sorcery spell, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Chains of Custody

Enchant creature you control
When Chains of Custody enters the battlefield, exile target nonland permanent an opponent controls until Chains of Custody leaves the battlefield.
Enchanted creature has ward {2}. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Essence of Antiquity

Disguise {2}{W} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Essence of Antiquity is turned face up, creatures you control gain hexproof until end of turn. Untap them.

Dungeon Delver

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

Kithkin Billyrider

Stunning Strike

Flash
Enchant creature
When Stunning Strike enters the battlefield, tap enchanted creature and remove it from combat.
As long as enchanted creature isn't legendary, it doesn't untap during its controller's untap step.

Biblioplex Kraken

When Biblioplex Kraken enters the battlefield, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)
Whenever Biblioplex Kraken attacks, you may return another creature you control to its owner's hand. If you do, Biblioplex Kraken can't be blocked this turn.

Sentinel's Eyes

Enchant creature
Enchanted creature gets +1/+1 and has vigilance.
Escape—{W}, Exile two other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Involuntary Cooldown

Tap up to two target artifacts and/or creatures. Put two stun counters on each of them. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Monk Class

(Gain the next level as a sorcery to add its ability.)
The second spell you cast each turn costs {1} less to cast.
{W}{U}: Level 2
When this Class becomes level 2, return up to one target nonland permanent to its owner's hand.
{1}{W}{U}: Level 3
At the beginning of your upkeep, exile the top card of your library. For as long as it remains exiled, it has "You may cast this card from exile as long as you've cast another spell this turn."

Tide Skimmer

Flying
Whenever you attack with two or more creatures with flying, draw a card.

Eccentric Apprentice

Flying
When Eccentric Apprentice enters the battlefield, 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.

Tidepool Turtle

{2}{U}: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Bar the Gate

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

Stasis Field

Enchant creature
Enchanted creature has base power and toughness 0/2, has defender, and loses all other abilities.

Haughty Djinn

Flying
Haughty Djinn's power is equal to the number of instant and sorcery cards in your graveyard.
Instant and sorcery spells you cast cost {1} less to cast.

Living Lectern

{1}, Sacrifice Living Lectern: Draw a card. Create a Sorcerer Role token attached to up to one other target creature you control. Activate only as a sorcery. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1 and has "Whenever this creature attacks, scry 1.")

Sol Ring

Slaughter the Strong

Each player chooses any number of creatures they control with total power 4 or less, then sacrifices all other creatures they control.

Majestic Metamorphosis

Until end of turn, target artifact or creature becomes a 4/4 Angel artifact creature and gains flying.
Draw a card.

Soulless Jailer

Permanent cards in graveyards can't enter the battlefield.
Players can't cast noncreature spells from graveyards or exile.

Benevolent Blessing

Flash
Enchant creature
As Benevolent Blessing enters the battlefield, choose a color.
Enchanted creature has protection from the chosen color. This effect doesn't remove Auras and Equipment you control that are already attached to it.

Air-Cult Elemental

Flying
Whirlwind — When Air-Cult Elemental enters the battlefield, return up to one other target creature to its owner's hand.

Idyllic Beachfront

({T}: Add {W} or {U}.)
Idyllic Beachfront enters the battlefield tapped.

Ornithopter

Radiant Solar

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

Expel the Interlopers

Choose a number between 0 and 10. Destroy all creatures with power greater than or equal to the chosen number.

Undercellar Sweep

When Undercellar Sweep enters the battlefield, you take the initiative.
Whenever you attack, if you or a player you're attacking has the initiative, you create two 1/1 white Soldier creature tokens that are tapped and attacking.

Scatter Ray

Counter target artifact or creature spell unless its controller pays {4}.

Veteran Dungeoneer

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

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.)

Wall of Denial

Defender, flying
Shroud (This creature can't be the target of spells or abilities.)

Snow-Covered Plains

The Battle of Bywater

Destroy all creatures with power 3 or greater. Then create a Food token for each creature you control. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Trailblazer's Torch

When Trailblazer's Torch enters the battlefield, 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.)

Greatsword of Tyr

Whenever equipped creature attacks, put a +1/+1 counter on it and tap up to one target creature defending player controls.
Equip {W} ({W}: Attach to target creature you control. Equip only as a sorcery.)

The Council of Four

Whenever a player draws their second card during their turn, you draw a card.
Whenever a player casts their second spell during their turn, you create a 2/2 white Knight creature token.

Moonfolk Puzzlemaker

Flying
Whenever Moonfolk Puzzlemaker becomes tapped, scry 1.

Senate Courier

Flying
{1}{W}: Senate Courier gains vigilance until end of turn.

Glory Bearers

Whenever another creature you control attacks, it gets +0/+1 until end of turn.

High Alert

Each creature you control assigns combat damage equal to its toughness rather than its power.
Creatures you control can attack as though they didn't have defender.
{2}{W}{U}: Untap target creature.

White Plume Adventurer

When White Plume Adventurer enters the battlefield, 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.