Spectacular Showdown

Put a double strike counter on target creature, then goad each creature that had a double strike counter put on it this way. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)
Overload {4}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Gruul Signet

Shiny Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Bothersome Quasit

Menace
Goaded creatures your opponents control can't block.
Whenever you cast a noncreature spell, goad target creature an opponent controls. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When Rancor is put into a graveyard from the battlefield, return Rancor to its owner's hand.

Colossification

Enchant creature
When Colossification enters, tap enchanted creature.
Enchanted creature gets +20/+20.

Bear Umbra

Enchant creature
Enchanted creature gets +2/+2 and has "Whenever this creature attacks, untap all lands you control."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Blackblade Reforged

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

Command Tower

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

Raised by Giants

Commander creatures you own have base power and toughness 10/10 and are Giants in addition to their other types.

Gaea's Gift

Put a +1/+1 counter on target creature you control. It gains reach, trample, hexproof, and indestructible until end of turn. (It can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Harmonize

Agitator Ant

At the beginning of your end step, each player may put two +1/+1 counters on a creature they control. Goad each creature that had counters put on it this way. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Rite of the Raging Storm

Creatures named Lightning Rager can't attack you or planeswalkers you control.
At the beginning of each player's upkeep, that player creates a 5/1 red Elemental creature token named Lightning Rager. It has trample, haste, and "At the beginning of the end step, sacrifice this creature."

Life of the Party

First strike, trample, haste
Whenever Life of the Party attacks, it gets +X/+0 until end of turn, where X is the number of creatures you control.
When Life of the Party enters, if it's not a token, each opponent creates a token that's a copy of it. The tokens are goaded for the rest of the game. (They attack each combat if able and attack a player other than you if able.)

Beast Within

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

Frontier Warmonger

Whenever one or more creatures attack one of your opponents or a planeswalker they control, those creatures gain menace until end of turn.

Mossfire Valley

Game Trail

As Game Trail enters, you may reveal a Mountain or Forest card from your hand. If you don't, Game Trail enters tapped.
{T}: Add {R} or {G}.

Fyndhorn Elves

Rootbound Crag

Rootbound Crag enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Blasphemous Act

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

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.

Geode Rager

First strike
Landfall — Whenever a land you control enters, goad each creature target player controls. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Krosan Grip

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Destroy target artifact or enchantment.

Forest

Zopandrel, Hunger Dominus

Reach
At the beginning of each combat, double the power and toughness of each creature you control until end of turn.
{G/P}{G/P}, Sacrifice two other creatures: Put an indestructible counter on Zopandrel, Hunger Dominus. ({G/P} can be paid with either {G} or 2 life.)

Jolene, the Plunder Queen

Whenever a player attacks one or more of your opponents, that attacking player creates a Treasure token.
If you would create one or more Treasure tokens, instead create those tokens plus an additional Treasure token.
Sacrifice five Treasures: Put five +1/+1 counters on Jolene.

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}

Mage Slayer

Whenever equipped creature attacks, it deals damage equal to its power to the player or planeswalker it's attacking.
Equip {3}

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Arcane Signet

Death Kiss

Whenever a creature an opponent controls attacks one of your opponents, double its power until end of turn.
{X}{X}{R}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
When Death Kiss becomes monstrous, goad up to X target creatures your opponents control.

Mithril Coat

Flash
Indestructible
When Mithril Coat enters, attach it to target legendary creature you control.
Equipped creature has indestructible.
Equip {3}

Avatar of Slaughter

All creatures have double strike and attack each combat if able.

Mountain

Khârn the Betrayer

Berzerker — Khârn the Betrayer attacks or blocks each combat if able.
Sigil of Corruption — When you lose control of Khârn the Betrayer, draw two cards.
The Betrayer — If damage would be dealt to Khârn the Betrayer, prevent that damage and an opponent of your choice gains control of it.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Tyvar's Stand

Target creature you control gets +X/+X and gains hexproof and indestructible until end of turn. (A creature with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Baeloth Barrityl, Entertainer

Creatures your opponents control with power less than Baeloth Barrityl's power are goaded. (They attack each combat if able and attack a player other than you if able.)
Whenever a goaded attacking or blocking creature dies, you create a Treasure token.
Choose a Background (You can have a Background as a second commander.)

Rogue's Passage

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

Goblin Spymaster

First strike
At the beginning of each opponent's end step, that player creates a 1/1 red Goblin creature token with "Creatures you control attack each combat if able."

Llanowar Elves

Xorn

If you would create one or more Treasure tokens, instead create those tokens plus an additional Treasure token.

Elvish Mystic

Rishkar's Expertise

Draw cards equal to the greatest power among creatures you control.
You may cast a spell with mana value 5 or less from your hand without paying its mana cost.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Kessig Wolf Run

{T}: Add {C}.
{X}{R}{G}, {T}: Target creature gets +X/+0 and gains trample until end of turn.

Domri, Anarch of Bolas

Creatures you control get +1/+0.
+1: Add {R} or {G}. Creature spells you cast this turn can't be countered.
−2: Target creature you control fights target creature you don't control.

Spire Garden

Spire Garden enters tapped unless you have two or more opponents.
{T}: Add {R} or {G}.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Evolving Wilds

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

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Kenrith's Transformation

Enchant creature
When Kenrith's Transformation enters, draw a card.
Enchanted creature loses all abilities and is a green Elk creature with base power and toughness 3/3. (It loses all other card types and creature types.)

Cinder Glade

({T}: Add {R} or {G}.)
Cinder Glade enters tapped unless you control two or more basic lands.

Swiftfoot Boots

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

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Mosswort Bridge

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.)
Mosswort Bridge enters tapped.
{T}: Add {G}.
{G}, {T}: You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

Curse of Opulence

Enchant player
Whenever enchanted player is attacked, create a Gold token. Each opponent attacking that player does the same. (A Gold token is an artifact with "Sacrifice this artifact: Add one mana of any color.")

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Vengeful Ancestor

Flying
Whenever Vengeful Ancestor enters or attacks, goad target creature. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)
Whenever a goaded creature attacks, it deals 1 damage to its controller.

Disrupt Decorum

Goad all creatures you don't control. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Bloodthirsty Blade

Equipped creature gets +2/+0 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
{1}: Attach Bloodthirsty Blade to target creature an opponent controls. Activate only as a sorcery.

Return of the Wildspeaker

Choose one —
• Draw cards equal to the greatest power among non-Human creatures you control.
• Non-Human creatures you control get +3/+3 until end of turn.

Rockfall Vale

Rockfall Vale enters tapped unless you control two or more other lands.
{T}: Add {R} or {G}.

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Lightning Greaves

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

Frenzied Saddlebrute

Haste
All creatures can attack your opponents and planeswalkers your opponents control as though those creatures had haste.

Loxodon Warhammer

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

Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter with your choice of a +1/+1 counter or haste.)

Guardian Augmenter

Flash
Commander creatures you control get +2/+2.
Commanders you control have hexproof.

Etali, Primal Sickness

Trample, indestructible
Whenever Etali, Primal Sickness deals combat damage to a player, they get that many poison counters. (A player with ten or more poison counters loses the game.)

Etali, Primal Conqueror

Trample
When Etali, Primal Conqueror enters, each player exiles cards from the top of their library until they exile a nonland card. You may cast any number of spells from among the nonland cards exiled this way without paying their mana costs.
{9}{G/P}: Transform Etali. Activate only as a sorcery.

Etali, Primal Conqueror // Etali, Primal Sickness

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Professional Face-Breaker

Menace
Whenever one or more creatures you control deal combat damage to a player, create a Treasure token.
Sacrifice a Treasure: Exile the top card of your library. You may play that card this turn.

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.

Gruul Turf

Gruul Turf enters tapped.
When Gruul Turf enters, return a land you control to its owner's hand.
{T}: Add {R}{G}.

Kodama's Reach

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Sol Ring

Etali, Primal Storm

Whenever Etali, Primal Storm attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.