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.)

Volcanic Strength

Enchant creature
Enchanted creature gets +2/+2 and has mountainwalk. (It can't be blocked as long as defending player controls a Mountain.)

Granite Grip

Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

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.

Vorrac Battlehorns

Equipped creature has trample and can't be blocked by more than one creature.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Goblin Bombardment

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

Eternal Warrior

Enchant creature
Enchanted creature has vigilance.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Sticky Fingers

Enchant creature
Enchanted creature has menace and "Whenever this creature deals combat damage to a player, create a Treasure token." (It can't be blocked except by two or more creatures. The token is an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
When enchanted creature dies, draw a card.

Cursed Mirror

{T}: Add {R}.
As Cursed Mirror enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

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.

Fervent Champion

First strike, haste
Whenever Fervent Champion attacks, another target attacking Knight you control gets +1/+0 until end of turn.
Equip abilities you activate that target Fervent Champion cost {3} less to activate.

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Shared Animosity

Whenever a creature you control attacks, it gets +1/+0 until end of turn for each other attacking creature that shares a creature type with it.

Solemn Simulacrum

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

Dragon Mantle

Enchant creature
When Dragon Mantle enters, draw a card.
Enchanted creature has "{R}: This creature gets +1/+0 until end of turn."

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Explorer's Scope

Whenever equipped creature attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Fury of the Horde

You may exile two red cards from your hand rather than pay this spell's mana cost.
Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Basilisk Collar

Equipped creature has deathtouch and lifelink.
Equip {2}

Lightning Greaves

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

Pandemonium

Whenever a creature enters, that creature's controller may have it deal damage equal to its power to any target of their choice.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Throne of the God-Pharaoh

At the beginning of your end step, each opponent loses life equal to the number of tapped creatures you control.

Arcane Signet

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

Berserkers' Onslaught

Attacking creatures you control have double strike.

Trailblazer's Boots

Equipped creature has nonbasic landwalk. (It can't be blocked as long as defending player controls a nonbasic land.)
Equip {2}

War Cadence

{X}{R}: This turn, creatures can't block unless their controller pays {X} for each blocking creature they control.

Spinerock Knoll

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
Spinerock Knoll enters tapped.
{T}: Add {R}.
{R}, {T}: You may play the exiled card without paying its mana cost if an opponent was dealt 7 or more damage this turn.

Sai of the Shinobi

Equipped creature gets +1/+1.
Whenever a creature you control enters, you may attach Sai of the Shinobi to it.
Equip {2}

Unexpected Windfall

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Battle Hymn

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.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Embercleave

Flash
This spell costs {1} less to cast for each attacking creature you control.
When Embercleave enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has double strike and trample.
Equip {3}

Claws of Valakut

Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control and has first strike.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Mana Geyser

Add {R} for each tapped land your opponents control.

Mountain

Tilonalli's Summoner

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Whenever Tilonalli's Summoner attacks, you may pay {X}{R}. If you do, create X 1/1 red Elemental creature tokens that are tapped and attacking. At the beginning of the next end step, exile those tokens unless you have the city's blessing.

Dictate of the Twin Gods

Flash
If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Kazuul's Toll Collector

{0}: Attach target Equipment you control to Kazuul's Toll Collector. Activate only as a sorcery.

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Toggo, Goblin Weaponsmith

Landfall — Whenever a land you control enters, create a colorless Equipment artifact token named Rock with "Equipped creature has '{1}, {T}, Sacrifice Rock: This creature deals 2 damage to any target'" and equip {1}.
Partner (You can have two commanders if both have partner.)

Myriad Landscape

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

Rogue's Gloves

Whenever equipped creature deals combat damage to a player, you may draw a card.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Champion of the Flame

Trample
Champion of the Flame gets +2/+2 for each Aura and Equipment attached to it.

Unquenchable Fury

Enchant creature
Enchanted creature has "Whenever this creature attacks, it deals X damage to defending player, where X is the number of cards in their hand."
When Unquenchable Fury is put into your graveyard from the battlefield, return it to your hand.

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Moraug, Fury of Akoum

Each creature you control gets +1/+0 for each time it has attacked this turn.
Landfall — Whenever a land you control enters, if it's your main phase, there's an additional combat phase after this phase. At the beginning of that combat, untap all creatures you control.

Injury

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Injury deals 2 damage to target creature and 2 damage to target player or planeswalker.

Insult

Damage can't be prevented this turn. If a source you control would deal damage this turn, it deals double that damage instead.

Insult // Injury

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice Hedron Archive: Draw two cards.

Big Score

Goblin War Paint

Enchant creature
Enchanted creature gets +2/+2 and has haste.

Seething Song

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Dust Corona

Enchant creature
Enchanted creature gets +2/+0 and can't be blocked by creatures with flying.

Hamletback Goliath

Whenever another creature enters, you may put X +1/+1 counters on Hamletback Goliath, where X is that creature's power.

Nettlecyst

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each artifact and/or enchantment you control.
Equip {2}

Culling Dais

{T}, Sacrifice a creature: Put a charge counter on Culling Dais.
{1}, Sacrifice Culling Dais: Draw a card for each charge counter on Culling Dais.

Prophetic Ravings

Enchant creature
Enchanted creature has haste and "{T}, Discard a card: Draw a card."

Hero's Blade

Equipped creature gets +3/+2.
Whenever a legendary creature you control enters, you may attach Hero's Blade to it.
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)

Cathartic Pyre

Choose one —
• Cathartic Pyre deals 3 damage to target creature or planeswalker.
• Discard up to two cards, then draw that many cards.

Blood Moon

Seize the Day

Untap target creature. After this main phase, there is an additional combat phase followed by an additional main phase.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tenza, Godo's Maul

Equipped creature gets +1/+1. As long as it's legendary, it gets an additional +2/+2. As long as it's red, it has trample.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Commander's Sphere

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

Ring of Valkas

Equipped creature has haste. (It can attack and {T} no matter when it came under your control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's red.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Harmonic Prodigy

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
If an ability of a Shaman or another Wizard you control triggers, that ability triggers an additional time.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

World at War

After the second main phase this turn, there's an additional combat phase followed by an additional main phase. At the beginning of that combat, untap all creatures that attacked this turn.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Mask of Memory

Whenever equipped creature deals combat damage to a player, you may draw two cards. If you do, discard a card.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Messenger's Speed

Enchant creature
Enchanted creature has trample and haste.

Kazuul's Cliffs

Kazuul's Cliffs enters tapped.
{T}: Add {R}.

Kazuul's Fury

As an additional cost to cast this spell, sacrifice a creature.
Kazuul's Fury deals damage equal to the sacrificed creature's power to any target.

Kazuul's Fury // Kazuul's Cliffs

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Combat Celebrant

If Combat Celebrant hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)

Valduk, Keeper of the Flame

At the beginning of combat on your turn, for each Aura and Equipment attached to Valduk, Keeper of the Flame, create a 3/1 red Elemental creature token with trample and haste. Exile those tokens at the beginning of the next end step.

Roadside Reliquary

{T}: Add {C}.
{2}, {T}, Sacrifice Roadside Reliquary: Draw a card if you control an artifact. Draw a card if you control an enchantment.

Wild Guess

As an additional cost to cast this spell, discard a card.
Draw two cards.

Tears of Rage

Cast this spell only during the declare attackers step.
Attacking creatures you control get +X/+0 until end of turn, where X is the number of attacking creatures. Sacrifice those creatures at the beginning of the next end step.

Thrill of Possibility

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Magus of the Wheel

{1}{R}, {T}, Sacrifice Magus of the Wheel: Each player discards their hand, then draws seven cards.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Gratuitous Violence

If a creature you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Giant Spectacle

Enchant creature
Enchanted creature gets +2/+1 and has menace.

Goldvein Pick

Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Massive Raid

Massive Raid deals damage to any target equal to the number of creatures you control.

Goblin War Drums

Creatures you control have menace. (They can't be blocked except by two or more creatures.)

Frenzied Rage

Enchant creature
Enchanted creature gets +2/+1 and has menace. (It can't be blocked except by two or more creatures.)

Bravado

Enchant creature
Enchanted creature gets +1/+1 for each other creature you control.

Savage Beating

Cast this spell only during your turn and only during combat.
Choose one —
• Creatures you control gain double strike until end of turn.
• Untap all creatures you control. After this phase, there is an additional combat phase.
Entwine {1}{R} (Choose both if you pay the entwine cost.)

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)