Éomer, Marshal of Rohan

Haste
Whenever one or more other attacking legendary creatures you control die, untap all creatures you control. After this phase, there is an additional combat phase. This ability triggers only once each turn.

Haunted Ridge

Haunted Ridge enters the battlefield tapped unless you control two or more other lands.
{T}: Add {B} or {R}.

Kindred Charge

Choose a creature type. For each creature you control of the chosen type, create a token that's a copy of that creature. Those tokens gain haste. Exile them at the beginning of the next end step.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

The Master, Multiplied

Myriad
The "legend rule" doesn't apply to creature tokens you control.
Triggered abilities you control can't cause you to sacrifice or exile creature tokens you control.

Read the Bones

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

Intimidation

Creatures you control have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Goblin War Drums

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

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Tainted Peak

{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.

Terminate

Destroy target creature. It can't be regenerated.

Plumb the Forbidden

As an additional cost to cast this spell, you may sacrifice one or more creatures. When you do, copy this spell for each creature sacrificed this way.
You draw a card and you lose 1 life.

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.")

Mana Geyser

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

Infernal Grasp

Destroy target creature. You lose 2 life.

Rogue's Passage

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

Command Tower

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

Rakdos Signet

Stensia Masquerade

Attacking creatures you control have first strike.
Whenever a Vampire you control deals combat damage to a player, put a +1/+1 counter on it.
Madness {2}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Go for the Throat

Talisman of Indulgence

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

Fervor

Creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Relic of Legends

{T}: Add one mana of any color.
Tap an untapped legendary creature you control: Add one mana of any color.

Lightning Greaves

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

Mountain

Command Beacon

{T}: Add {C}.
{T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

Big Score

Luxury Suite

Luxury Suite enters the battlefield tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Orthion, Hero of Lavabrink

{1}{R}, {T}: Create a token that's a copy of another target creature you control. It gains haste. Sacrifice it at the beginning of the next end step. Activate only as a sorcery.
{6}{R}{R}{R}, {T}: Create five tokens that are copies of another target creature you control. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.

Bitter Triumph

As an additional cost to cast this spell, discard a card or pay 3 life.
Destroy target creature or planeswalker.

Ashling's Prerogative

As Ashling's Prerogative enters the battlefield, choose odd or even. (Zero is even.)
Each creature with mana value of the chosen quality has haste.
Each creature without mana value of the chosen quality enters the battlefield tapped.

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.

Swiftfoot Boots

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

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Rousing Refrain

Add {R} for each card in target opponent's hand. Until end of turn, you don't lose this mana as steps and phases end. Exile Rousing Refrain with three time counters on it.
Suspend 3—{1}{R} (Rather than cast this card from your hand, you may pay {1}{R} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Black Market Connections

At the beginning of your precombat main phase, choose one or more —
• Sell Contraband — Create a Treasure token. You lose 1 life.
• Buy Information — Draw a card. You lose 2 life.
• Hire a Mercenary — Create a 3/2 colorless Shapeshifter creature token with changeling. You lose 3 life. (It has every creature type.)

Sol Ring

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

War Cadence

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

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Blood Crypt

({T}: Add {B} or {R}.)
As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Thrill of Possibility

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

Dragonskull Summit

Dragonskull Summit enters the battlefield tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Hammer of Purphoros

Creatures you control have haste.
{2}{R}, {T}, Sacrifice a land: Create a 3/3 colorless Golem enchantment artifact creature token.

Ogre Battledriver

Whenever another creature enters the battlefield under your control, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Honor-Worn Shaku

{T}: Add {C}.
Tap an untapped legendary permanent you control: Untap Honor-Worn Shaku.

World at War

After the first postcombat 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.)

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.)

Pyretic Ritual

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.

Bedevil

Destroy target artifact, creature, or planeswalker.

Bitter Reunion

When Bitter Reunion enters the battlefield, you may discard a card. If you do, draw two cards.
{1}, Sacrifice Bitter Reunion: Creatures you control gain haste until end of turn.

Swamp

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.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Dark Ritual

Seething Song

Thought Vessel

Demand Answers

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

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.

Dolmen Gate

Prevent all combat damage that would be dealt to attacking creatures you control.

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.)

Cover of Darkness

As Cover of Darkness enters the battlefield, choose a creature type.
Creatures of the chosen type have fear. (They can't be blocked except by artifact creatures and/or black creatures.)

Sign in Blood

Target player draws two cards and loses 2 life.

Bedlam

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Anger

Haste
As long as Anger is in your graveyard and you control a Mountain, creatures you control have haste.

Blasphemous Act

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

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Roaming Throne

Ward {2}
As Roaming Throne enters the battlefield, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Mass Hysteria

Jaxis, the Troublemaker

{R}, {T}, Discard a card: Create a token that's a copy of another target creature you control. It gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step. Activate only as a sorcery.
Blitz {1}{R} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Purphoros, Bronze-Blooded

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Other creatures you control have haste.
{2}{R}: You may put a red creature card or an artifact creature card from your hand onto the battlefield. Sacrifice it at the beginning of the next end step.

Night's Whisper

Stinging Study

You draw X cards and you lose X life, where X is the mana value of a commander you own on the battlefield or in the command zone.