Karlach, Fury of Avernus

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase.
Choose a Background (You can have a Background as a second commander.)

Defiant Strike

Target creature gets +1/+0 until end of turn.
Draw a card.

Guided Strike

Target creature gets +1/+0 and gains first strike until end of turn.
Draw a card.

Evolving Wilds

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

Sejiri Glacier

Sejiri Glacier enters tapped.
{T}: Add {W}.

Sejiri Shelter

Target creature you control gains protection from the color of your choice until end of turn.

Sejiri Shelter // Sejiri Glacier

Sunforger

Equipped creature gets +4/+0.
{R}{W}, Unattach Sunforger: Search your library for a red or white instant card with mana value 4 or less and cast that card without paying its mana cost. Then shuffle.
Equip {3}

Witch's Mark

You may discard a card. If you do, draw two cards.
Create a Wicked Role token attached to up to one target creature you control. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1. When this Aura is put into a graveyard, each opponent loses 1 life.)

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Leonin Lightscribe

Magecraft — Whenever you cast or copy an instant or sorcery spell, creatures you control get +1/+1 until end of turn.

Might of the Meek

Target creature gains trample until end of turn. It also gets +1/+0 until end of turn if you control a Mouse.
Draw a card.

Bandage

Prevent the next 1 damage that would be dealt to any target this turn.
Draw a card.

Cabaretti Courtyard

When Cabaretti Courtyard enters, sacrifice it. When you do, search your library for a basic Mountain, Forest, or Plains card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Heal

Prevent the next 1 damage that would be dealt to any target this turn.
Draw a card at the beginning of the next turn's upkeep.

Temple of Triumph

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {R} or {W}.

Restless Bivouac

Restless Bivouac enters tapped.
{T}: Add {R} or {W}.
{1}{R}{W}: Restless Bivouac becomes a 2/2 red and white Ox creature until end of turn. It's still a land.
Whenever Restless Bivouac attacks, put a +1/+1 counter on target creature you control.

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Drannith Magistrate

Your opponents can't cast spells from anywhere other than their hands.

Brute Force

Target creature gets +3/+3 until end of turn.

Boros Garrison

Boros Garrison enters tapped.
When Boros Garrison enters, return a land you control to its owner's hand.
{T}: Add {R}{W}.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Niveous Wisps

Target creature becomes white until end of turn. Tap that creature.
Draw a card.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Stroke of Midnight

Destroy target nonland permanent. Its controller creates a 1/1 white Human creature token.

Sheltering Light

Target creature gains indestructible until end of turn. Scry 1. (Damage and effects that say "destroy" don't destroy the creature.)

Titan's Strength

Target creature gets +3/+1 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Sunscorched Divide

Mavinda, Students' Advocate

Flying
{0}: You may cast target instant or sorcery card from your graveyard this turn. If that spell doesn't target a creature you control, it costs {8} more to cast this way. If that spell would be put into your graveyard, exile it instead. Activate only once each turn. (You still pay the spell's costs. Timing rules for the spell still apply.)

Lorehold Campus

Lorehold Campus enters tapped.
{T}: Add {R} or {W}.
{4}, {T}: Scry 1.

Precursor Golem

When Precursor Golem enters, create two 3/3 colorless Golem artifact creature tokens.
Whenever a player casts an instant or sorcery spell that targets only a single Golem, that player copies that spell for each other Golem that spell could target. Each copy targets a different one of those Golems.

Fight as One

Choose one or both —
• Target Human creature you control gets +1/+1 and gains indestructible until end of turn.
• Target non-Human creature you control gets +1/+1 and gains indestructible until end of turn.

Divine Reckoning

Each player chooses a creature they control. Destroy the rest.
Flashback {5}{W}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Expedite

Target creature gains haste until end of turn.
Draw a card.

Mountain

Castle Embereth

Castle Embereth enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Loran's Escape

Target artifact or creature gains hexproof and indestructible until end of turn. Scry 1.

Raucous Carnival

Raucous Carnival enters tapped unless a player has 13 or less life.
{T}: Add {R} or {W}.

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Wind-Scarred Crag

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {R} or {W}.

Darksteel Mutation

Enchant creature
Enchanted creature is an Insect artifact creature with base power and toughness 0/1 and has indestructible, and it loses all other abilities, card types, and creature types.

Alpine Meadow

({T}: Add {R} or {W}.)
Alpine Meadow enters tapped.

Day of Judgment

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Blacksmith's Skill

Target permanent gains hexproof and indestructible until end of turn. If it's an artifact creature, it gets +2/+2 until end of turn.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Rabid Gnaw

Target creature you control gets +1/+0 until end of turn. Then it deals damage equal to its power to target creature you don't control.

Balefire Liege

Other red creatures you control get +1/+1.
Other white creatures you control get +1/+1.
Whenever you cast a red spell, Balefire Liege deals 3 damage to target player or planeswalker.
Whenever you cast a white spell, you gain 3 life.

Tragic Arrogance

For each player, you choose from among the permanents that player controls an artifact, a creature, an enchantment, and a planeswalker. Then each player sacrifices all other nonland permanents they control.

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.)

Austere Command

Choose two —
• Destroy all artifacts.
• Destroy all enchantments.
• Destroy all creatures with mana value 3 or less.
• Destroy all creatures with mana value 4 or greater.

Fall of the Hammer

Target creature you control deals damage equal to its power to another target creature.

Soul's Fire

Target creature you control deals damage equal to its power to any target.

Terramorphic Expanse

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

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. Talisman of Conviction deals 1 damage to you.

Blazing Crescendo

Target creature gets +3/+1 until end of turn.
Exile the top card of your library. Until the end of your next turn, you may play that card.

Arcane Signet

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

Relentless Assault

Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase.

Shelter

Target creature you control gains protection from the color of your choice until end of turn.
Draw a card.

Waltz of Rage

Target creature you control deals damage equal to its power to each other creature. Until end of turn, whenever a creature you control dies, exile the top card of your library. You may play it until the end of your next turn.

Boros Signet

Fists of Flame

Draw a card. Until end of turn, target creature gains trample and gets +1/+0 for each card you've drawn this turn. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

Tear

Destroy target enchantment.
Fuse (You may cast one or both halves of this card from your hand.)

Wear

Destroy target artifact.
Fuse (You may cast one or both halves of this card from your hand.)

Wear // Tear

Rustvale Bridge

Rustvale Bridge enters tapped.
Indestructible
{T}: Add {R} or {W}.

Ancestors' Aid

Target creature gets +2/+0 and gains first strike until end of turn.
Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Farewell

Choose one or more —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all graveyards.

Boros Charm

Choose one —
• Boros Charm deals 4 damage to target player or planeswalker.
• Permanents you control gain indestructible until end of turn.
• Target creature gains double strike until end of turn.

Storm-Kiln Artist

Storm-Kiln Artist gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Psychotic Fury

Target multicolored creature gains double strike until end of turn.
Draw a card.

Sacred Peaks

({T}: Add {R} or {W}.)
Sacred Peaks enters tapped.

Crimson Wisps

Target creature becomes red and gains haste until end of turn. (It can attack and {T} this turn.)
Draw a card.

Battlefield Forge

{T}: Add {C}.
{T}: Add {R} or {W}. Battlefield Forge deals 1 damage to you.

Feather, the Redeemed

Flying
Whenever you cast an instant or sorcery spell that targets a creature you control, exile that card instead of putting it into your graveyard as it resolves. If you do, return it to your hand at the beginning of the next end step.

Ancient Amphitheater

As Ancient Amphitheater enters, you may reveal a Giant card from your hand. If you don't, Ancient Amphitheater enters tapped.
{T}: Add {R} or {W}.

Plains

Sudden Breakthrough

Gods Willing

Target creature you control gains protection from the color of your choice until end of turn. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything of that color.)
Scry 1.

Take Up the Shield

Put a +1/+1 counter on target creature. It gains lifelink and indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Sol Ring

Furycalm Snarl

As Furycalm Snarl enters, you may reveal a Mountain or Plains card from your hand. If you don't, Furycalm Snarl enters tapped.
{T}: Add {R} or {W}.

Deflecting Palm

The next time a source of your choice would deal damage to you this turn, prevent that damage. If damage is prevented this way, Deflecting Palm deals that much damage to that source's controller.

Cleansing Nova

Choose one —
• Destroy all creatures.
• Destroy all artifacts and enchantments.

Angelfire Ignition

Put two +1/+1 counters on target creature. It gains vigilance, trample, lifelink, indestructible, and haste until end of turn.
Flashback {2}{R}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Boros Guildgate

This land enters tapped.
{T}: Add {R} or {W}.

Wrath of God

Destroy all creatures. They can't be regenerated.

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Command Tower

Ghostly Prison

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

Reckless Rage

Reckless Rage deals 4 damage to target creature you don't control and 2 damage to target creature you control.

Needle Spires

Needle Spires enters tapped.
{T}: Add {R} or {W}.
{2}{R}{W}: Needle Spires becomes a 2/1 red and white Elemental creature with double strike until end of turn. It's still a land.

Stone Quarry

Stone Quarry enters tapped.
{T}: Add {R} or {W}.

Resurgence

Creatures you control gain first strike and vigilance until end of turn. After this main phase, there is an additional combat phase followed by an additional main phase.

Response

Response deals 5 damage to target attacking or blocking creature.

Response // Resurgence

Sentinel Tower

Whenever an instant or sorcery spell is cast during your turn, Sentinel Tower deals damage to any target equal to 1 plus the number of instant and sorcery spells cast before that spell this turn.

Ashmouth Dragon

Flying
Whenever you cast an instant or sorcery spell, Ashmouth Dragon deals 2 damage to any target.

Smoldering Egg

Defender
Whenever you cast an instant or sorcery spell, put a number of ember counters on Smoldering Egg equal to the amount of mana spent to cast that spell. Then if Smoldering Egg has seven or more ember counters on it, remove them and transform Smoldering Egg.