Lethe Lake

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

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.

Goldmeadow

Whenever a land enters, that land's controller creates three 0/1 white Goat creature tokens.
Whenever chaos ensues, create a 0/1 white Goat creature token.

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.

Talon Gates

Any time you could cast a sorcery, you may exile a nonland card from your hand with X time counters on it, where X is its mana value. If the exiled card doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, the player may cast it without paying its mana cost. If it's a creature, it has haste.)
Whenever chaos ensues, remove two time counters from each suspended card you own.

Norn's Dominion

When you planeswalk away from Norn's Dominion, destroy each nonland permanent without a fate counter on it, then remove all fate counters from all permanents.
Whenever chaos ensues, you may put a fate counter on target permanent.

The Hippodrome

All creatures get -5/-0.
Whenever chaos ensues, you may destroy target creature if its power is 0 or less.

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.

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.

Murasa

Whenever a nontoken creature enters, its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever chaos ensues, target land becomes a 4/4 creature that's still a land.

Eloren Wilds

Whenever a player taps a permanent for mana, that player adds one mana of any type that permanent produced.
Whenever chaos ensues, target player can't cast spells until a player planeswalks.

Grove of the Dreampods

When you planeswalk to Grove of the Dreampods and at the beginning of your upkeep, reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield and the rest on the bottom of your library in a random order.
Whenever chaos ensues, return target creature card from your graveyard to the battlefield.

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.

Edge of Malacol

If a creature you control would untap during your untap step, put two +1/+1 counters on it instead.
Whenever chaos ensues, untap each creature you control.

Gavony

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

Fractured Powerstone

{T}: Add {C}.
{T}: Roll the planar die. Activate only as a sorcery.

Spatial Merging

When you encounter Spatial Merging, reveal cards from the top of your planar deck until you reveal two plane cards. Simultaneously planeswalk to both of them. Put all other cards revealed this way on the bottom of your planar deck in any order.

Undercity Reaches

Whenever a creature deals combat damage to a player, its controller may draw a card.
Whenever chaos ensues, you have no maximum hand size for the rest of the game.

Interplanar Tunnel

When you encounter Interplanar Tunnel, reveal cards from the top of your planar deck until you reveal five plane cards. Put a plane card from among them on top of your planar deck, then put the rest of the revealed cards on the bottom in a random order. (Then planeswalk away from this phenomenon.)

Panopticon

When you planeswalk to Panopticon, draw a card.
At the beginning of your draw step, draw an additional card.
Whenever chaos ensues, draw a card.

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.

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.

Feeding Grounds

Red spells cost {1} less to cast.
Green spells cost {1} less to cast.
Whenever chaos ensues, put X +1/+1 counters on target creature, where X is that creature's mana value.

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.

Pools of Becoming

At the beginning of your end step, put the cards in your hand on the bottom of your library in any order, then draw that many cards.
Whenever chaos ensues, reveal the top three cards of your planar deck. Each of the revealed cards' chaos abilities triggers. Then put the revealed cards on the bottom of your planar deck in any order.

Jund

Whenever a player casts a creature spell that's black, red, or green, it gains devour 5. (As the creature enters, its controller may sacrifice any number of creatures of their choice. The creature enters with five times that many +1/+1 counters on it.)
Whenever chaos ensues, create two 1/1 red Goblin creature tokens.

Lair of the Ashen Idol

At the beginning of your upkeep, sacrifice a creature. If you can't, planeswalk.
Whenever chaos ensues, any number of target players each create a 2/2 black Zombie creature token.

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.

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.

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.

Naar Isle

At the beginning of your upkeep, put a flame counter on Naar Isle, then Naar Isle deals damage to you equal to the number of flame counters on it.
Whenever chaos ensues, Naar Isle deals 3 damage to target player or planeswalker.

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.

Nephalia

At the beginning of your end step, mill seven cards. Then return a card at random from your graveyard to your hand.
Whenever chaos ensues, return target card from your graveyard to your hand.

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.

Naya

You may play any number of lands on each of your turns.
Whenever chaos ensues, target red, green, or white creature you control gets +1/+1 until end of turn for each land you control.

Quicksilver Sea

When you planeswalk to Quicksilver Sea and at the beginning of your upkeep, scry 4. (Look at the top four cards of your library, then put any number of them on the bottom and the rest on top in any order.)
Whenever chaos ensues, reveal the top card of your library. You may play it without paying its mana cost.

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.

Skybreen

Players play with the top card of their libraries revealed.
Spells that share a card type with the top card of a library can't be cast.
Whenever chaos ensues, target player loses life equal to the number of cards in their hand.

The Eon Fog

Players skip their untap steps.
Whenever chaos ensues, untap all permanents you control.

Stairs to Infinity

Players have no maximum hand size.
Whenever you roll the planar die, draw a card.
Whenever chaos ensues, reveal the top card of your planar deck. You may put it on the bottom of your planar deck.

Morphic Tide

When you encounter Morphic Tide, each player shuffles all permanents they own into their library, then reveals that many cards from the top of their library. Each player puts all artifact, creature, land, and planeswalker cards revealed this way onto the battlefield, then does the same for enchantment cards, then puts all cards revealed this way that weren't put onto the battlefield on the bottom of their library in any order. (Then planeswalk away from this phenomenon.)