Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Arena of Glory

This land enters tapped unless you control a Mountain.
{T}: Add {R}.
{R}, {T}, Exert this land: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

Blade of Selves

Equipped creature has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Equip {4}

Sword of Feast and Famine

Equipped creature gets +2/+2 and has protection from black and from green.
Whenever equipped creature deals combat damage to a player, that player discards a card and you untap all lands you control.
Equip {2}

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Reverberate

Copy target instant or sorcery spell. You may choose new targets for the copy.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Ruby Medallion

Red spells you cast cost {1} less to cast.

Balefire Dragon

Flying
Whenever this creature deals combat damage to a player, it deals that much damage to each creature that player controls.

Chandra's Ignition

Target creature you control deals damage equal to its power to each other creature and each opponent.

Reforge the Soul

Each player discards their hand, then draws seven cards.
Miracle {1}{R} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Sarkhan, the Dragonspeaker

+1: Until end of turn, Sarkhan becomes a legendary 4/4 red Dragon creature with flying, indestructible, and haste. (He doesn't lose loyalty while he's not a planeswalker.)
−3: Sarkhan deals 4 damage to target creature.
−6: You get an emblem with "At the beginning of your draw step, draw two additional cards" and "At the beginning of your end step, discard your hand."

Burning Sun's Avatar

When this creature enters, it deals 3 damage to target opponent or planeswalker and 3 damage to up to one target creature.

Rising of the Day

Creatures you control have haste.
Legendary creatures you control get +1/+0.

Etali, Primal Storm

Whenever Etali 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.

Throne of Eldraine

As Throne of Eldraine enters, choose a color.
{T}: Add four mana of the chosen color. Spend this mana only to cast monocolored spells of that color.
{3}, {T}: Draw two cards. Spend only mana of the chosen color to activate this ability.

Otepec Huntmaster

Dinosaur spells you cast cost {1} less to cast.
{T}: Target Dinosaur gains haste until end of turn.

Plaza of Heroes

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell.
{T}: Add one mana of any color among legendary permanents you control.
{3}, {T}, Exile this land: Target legendary creature gains hexproof and indestructible until end of turn.

Rampaging Ceratops

This creature can't be blocked except by three or more creatures.

Capricious Hellraiser

This spell costs {3} less to cast if you have nine or more cards in your graveyard.
Flying
When this creature enters, exile three cards at random from your graveyard. Choose a noncreature, nonland card from among them and copy it. You may cast the copy without paying its mana cost.

Sol Ring

Imposing Grandeur

Each player may discard their hand and draw cards equal to the greatest mana value of a commander they own on the battlefield or in the command zone.

Big Score

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 token: Add one mana of any color.")

Unexpected Windfall

Thought Vessel

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

Impulsivity

When this creature enters, you may cast target instant or sorcery card from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.
Encore {7}{R}{R} ({7}{R}{R}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Marauding Raptor

Creature spells you cast cost {1} less to cast.
Whenever another creature you control enters, this creature deals 2 damage to it. If a Dinosaur is dealt damage this way, this creature gets +2/+0 until end of turn.

Roaming Throne

Ward {2}
As this creature enters, choose a creature type.
This creature 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.

Kindle the Inner Flame

Create a token that's a copy of target creature you control, except it has haste and "At the beginning of the end step, sacrifice this token."
Flashback—{1}{R}, Behold three Elementals. (You may cast this card from your graveyard for its flashback cost. Then exile it. To behold an Elemental, choose an Elemental you control or reveal an Elemental card from your hand.)

Chandra, Torch of Defiance

+1: Exile the top card of your library. You may cast that card. If you don't, Chandra deals 2 damage to each opponent.
+1: Add {R}{R}.
−3: Chandra deals 4 damage to target creature.
−7: You get an emblem with "Whenever you cast a spell, this emblem deals 5 damage to any target."

Savage Beating

Cast this spell only during combat on your turn.
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.)

Tibalt's Trickery

Counter target spell. Choose 1, 2, or 3 at random. Its controller mills that many cards, then exiles cards from the top of their library until they exile a nonland card with a different name than that spell. They may cast that card without paying its mana cost. Then they put the exiled cards on the bottom of their library in a random order.

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Worn Powerstone

This artifact enters tapped.
{T}: Add {C}{C}.

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.

Urabrask the Hidden

Creatures you control have haste.
Creatures your opponents control enter tapped.

Mana Geyser

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

Flaming Tyrannosaurus

Menace
Paradox — Whenever you cast a spell from anywhere other than your hand, this creature deals 3 damage to any target. Then put a +1/+1 counter on this creature.
When this creature dies, it deals damage equal to its power to each opponent.

Thran Dynamo

Blasphemous Act

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

Terror of the Peaks

Flying
Spells your opponents cast that target this creature cost an additional 3 life to cast.
Whenever another creature you control enters, this creature deals damage equal to that creature's power to any target.

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.)

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Passionate Archaeologist

Commander creatures you own have "Whenever you cast a spell from exile, this creature deals damage equal to that spell's mana value to target opponent."

Dragonmaster Outcast

At the beginning of your upkeep, if you control six or more lands, create a 5/5 red Dragon creature token with flying.

Treasure Nabber

Whenever an opponent taps an artifact for mana, gain control of that artifact until the end of your next turn.

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}

Everflowing Chalice

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

Lizard Blades

Double strike
Equipped creature has double strike.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Burnished Hart

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

Gilded Lotus

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Sawhorn Nemesis

As this creature enters, choose a player.
If a source would deal damage to the chosen player or a permanent they control, it deals double that damage instead.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Nalfeshnee

Flying
Whenever you cast a spell from exile, copy it. You may choose new targets for the copy. If it's a permanent spell, the copy gains haste and "At the beginning of the end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)

Drakuseth, Maw of Flames

Flying
Whenever Drakuseth attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Cavern of Souls

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

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 token: Add one mana of any color.")

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.)

Mountain

Rogue's Passage

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

Powerbalance

Whenever an opponent casts a spell, you may reveal the top card of your library. If you do, you may cast that card without paying its mana cost if the two spells have the same mana value.

Lavaspur Boots

Equipped creature gets +1/+0 and has haste and ward {1}. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
Equip {1}

Lightning Greaves

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

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, this creature deals 1 damage to that creature's controller.

Bolt Bend

This spell costs {3} less to cast if you control a creature with power 4 or greater.
Change the target of target spell or ability with a single target.

Gogo, Mysterious Mime

At the beginning of combat on your turn, you may have Gogo become a copy of another target creature you control until end of turn, except its name is Gogo, Mysterious Mime. If you do, Gogo and that creature each get +2/+0 and gain haste until end of turn and attack this turn if able.

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.")

Extraplanar Lens

Imprint — When this artifact enters, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.

Field of Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

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.)

Shinka, the Bloodsoaked Keep

{T}: Add {R}.
{R}, {T}: Target legendary creature gains first strike until end of turn.

Hellkite Courser

Flying
When this creature enters, you may put a commander you own from the command zone onto the battlefield. It gains haste. Return it to the command zone at the beginning of the next end step.

Charging Monstrosaur

Flameshadow Conjuring

Whenever a nontoken creature you control enters, you may pay {R}. If you do, create a token that's a copy of that creature. That token gains haste. Exile it at the beginning of the next end step.