Astral Arena

No more than one creature can attack each combat.
No more than one creature can block each combat.
Whenever chaos ensues, Astral Arena deals 2 damage to each creature.

Esper

Artifact spells cost {1} less to cast.
Whenever chaos ensues, creatures you control that are white, blue, and/or black become artifacts in addition to their other types until end of turn. Then each artifact creature you control gains vigilance, menace, and lifelink until end of turn.

Selesnya Loft Gardens

If an effect would create one or more tokens, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent, it puts twice that many of those counters on that permanent instead.
Whenever chaos ensues, until end of turn, whenever you tap a land for mana, add one mana of any type that land produced.

Tember City

Whenever a player taps a land for mana, Tember City deals 1 damage to that player.
Whenever chaos ensues, each other player sacrifices a nonland permanent of their choice.

Isle of Vesuva

Whenever a nontoken creature enters, its controller creates a token that's a copy of that creature.
Whenever chaos ensues, destroy target creature and all other creatures with the same name as that creature.

Towashi

Modified creatures you control have trample and "Whenever this creature deals combat damage to a player or planeswalker, draw a card." (Equipment, Auras you control, and counters are modifications.)
Whenever chaos ensues, distribute three +1/+1 counters among one, two, or three target creatures you control.

Academy at Tolaria West

At the beginning of your end step, if you have no cards in hand, draw seven cards.
Whenever chaos ensues, discard your hand.

Paliano

When one or more creatures you control deal combat damage to a player, if there is no monarch, you become the monarch.
Whenever chaos ensues, create a 1/1 black Assassin creature token with deathtouch and haste.

Norn's Seedcore

When you planeswalk to Norn's Seedcore, chaos ensues.
Whenever chaos ensues, reveal cards from the top of your planar deck until you reveal a plane card. Planeswalk to it, except don't planeswalk away from any plane. Put the rest of the revealed cards on the bottom of your planar deck in any order.

Immersturm

Whenever a creature enters, that creature's controller may have it deal damage equal to its power to any target of their choice.
Whenever chaos ensues, exile target creature, then return it to the battlefield under its owner's control.

Celestine Reef

Creatures without flying or islandwalk can't attack.
Whenever chaos ensues, until a player planeswalks, you can't lose the game and your opponents can't win the game.

Onakke Catacomb

All creatures are black and have deathtouch.
Whenever chaos ensues, creatures you control get +1/+0 and gain first strike until end of turn.

Sokenzan

All creatures get +1/+1 and have haste.
Whenever chaos ensues, untap all creatures that attacked this turn. If it's a main phase, there is an additional combat phase after this phase, followed by an additional main phase.

Bloodhill Bastion

Whenever a creature enters, it gains double strike and haste until end of turn.
Whenever chaos ensues, exile target nontoken creature you control, then return it to the battlefield under your control.

Lethe Lake

At the beginning of your upkeep, mill ten cards.
Whenever chaos ensues, target player mills ten cards.

Orzhova

When you planeswalk away from Orzhova, each player returns all creature cards from their graveyard to the battlefield.
Whenever chaos ensues, for each opponent, exile up to one target creature card from that player's graveyard.

Trail of the Mage-Rings

Instant and sorcery spells have rebound. (The spell's controller exiles the spell as it resolves if they cast it from their hand. At the beginning of that player's next upkeep, they may cast that card from exile without paying its mana cost.)
Whenever chaos ensues, you may search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Prahv

If you cast a spell this turn, you can't attack with creatures.
If you attacked with creatures this turn, you can't cast spells.
Whenever chaos ensues, you gain life equal to the number of cards in your hand.

Mirrored Depths

Whenever a player casts a spell, that player flips a coin. If the player loses the flip, counter that spell.
Whenever chaos ensues, target player reveals the top card of their library. If it's a nonland card, you may cast it without paying its mana cost.

Strixhaven

Instant and sorcery spells players cast have demonstrate. (Whenever a player casts an instant or sorcery spell, they may copy it. If they do, they choose an opponent to also copy it. Players may choose new targets for their copies.)
Whenever chaos ensues, return up to one target instant or sorcery card from a graveyard to its owner's hand.

The Western Cloud

Prevent all damage that would be dealt to creatures and planeswalkers you control.
Whenever chaos ensues, create three tapped Treasure tokens. They each deal 1 damage to each creature and each planeswalker.

The Caldaia

Creature spells you cast from your hand have blitz {3}. (If you cast a 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.)
Whenever chaos ensues, return target creature card from your graveyard to your hand.

The Golden City of Orazca

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Whenever one or more creatures you control deal combat damage to a player, create a Treasure token. Then draw a card if you have the city's blessing.
Whenever chaos ensues, you may put a permanent card from your hand onto the battlefield tapped.

Sanctum of Serra

When you planeswalk away from Sanctum of Serra, destroy all nonland permanents.
Whenever chaos ensues, you may have your life total become 20.

Orochi Colony

Whenever a creature you control deals combat damage to a player, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever chaos ensues, target creature can't be blocked this turn.

The Great Aerie

When you planeswalk to The Great Aerie and at the beginning of your upkeep, bolster 3. (Choose a creature with the least toughness among creatures you control and put three +1/+1 counters on it.)
Whenever chaos ensues, choose up to one target creature you control and up to one target creature an opponent controls. Each of those creatures deals damage equal to its toughness to the other.

Stronghold Furnace

If a source would deal damage to a permanent or player, it deals double that damage instead.
Whenever chaos ensues, Stronghold Furnace deals 1 damage to any target.

Stensia

Whenever a creature deals damage to one or more players for the first time each turn, put a +1/+1 counter on it.
Whenever chaos ensues, each creature you control gains "{T}: This creature deals 1 damage to target player or planeswalker" until end of turn.

Bant

All creatures have exalted. (Whenever a creature attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents its controller controls.)
Whenever chaos ensues, put a divinity counter on target green, white, or blue creature. That creature has indestructible for as long as it has a divinity counter on it.

The Great Forest

Each creature assigns combat damage equal to its toughness rather than its power.
Whenever chaos ensues, creatures you control get +0/+2 and gain trample until end of turn.

Takenuma

Whenever a creature leaves the battlefield, its controller draws a card.
Whenever chaos ensues, return target creature you control to its owner's hand.

Horizon Boughs

All permanents untap during each player's untap step.
Whenever chaos ensues, you may search your library for up to three basic land cards, put them onto the battlefield tapped, then shuffle.

Minamo

Whenever a player casts a spell, that player may draw a card.
Whenever chaos ensues, each player may return a blue card from their graveyard to their hand.

The Aether Flues

When you planeswalk to The Aether Flues and at the beginning of your upkeep, you may sacrifice a creature. If you do, reveal cards from the top of your library until you reveal a creature card, put that card onto the battlefield, then shuffle all other cards revealed this way into your library.
Whenever chaos ensues, you may put a creature card from your hand onto the battlefield.

The Maelstrom

When you planeswalk to The Maelstrom and at the beginning of your upkeep, you may reveal the top card of your library. If it's a permanent card, you may put it onto the battlefield. If you revealed a card but didn't put it onto the battlefield, put it on the bottom of your library.
Whenever chaos ensues, return target permanent card from your graveyard to the battlefield.

Gavony

All creatures have vigilance.
Whenever chaos ensues, creatures you control gain indestructible until end of turn.

Izzet Steam Maze

Whenever a player casts an instant or sorcery spell, that player copies it. The player may choose new targets for the copy.
Whenever chaos ensues, instant and sorcery spells you cast this turn cost {3} less to cast.