Ood Sphere

Song of the Ood — Noncreature spells have convoke. (A player's creatures can help cast those spells. Each creature they tap while casting a noncreature spell pays for {1} or one mana of that creature's color.)
Red-Eye — Whenever chaos ensues, for each opponent, goad up to one target creature that opponent controls. Until your next turn, those creatures can't become tapped unless they're being declared as attackers.

Glimmervoid Basin

Whenever a player casts an instant or sorcery spell with a single target, that player copies that spell for each other spell, permanent, card not on the battlefield, and/or player the spell could target. Each copy targets a different one of them.
Whenever chaos ensues, choose target creature. Each player except that creature's controller creates a token that's a copy of that creature.

Chaotic Aether

When you encounter Chaotic Aether, each blank roll of the planar die is a {CHAOS} roll until a player planeswalks away from a plane. (Then planeswalk away from this phenomenon.)

Otaria

Instant and sorcery cards in graveyards have flashback. The flashback cost is equal to the card's mana cost. (Its owner may cast the card from their graveyard for its mana cost. Then they exile it.)
Whenever chaos ensues, take an extra turn after this one.

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.

Planewide Disaster

When you encounter Planewide Disaster, destroy all creatures. (Then planeswalk away from this phenomenon.)

Caught in a Parallel Universe

When you encounter Caught in a Parallel Universe, each player chooses a creature controlled by the player to their left. Each player creates a token that's a copy of the creature they chose, except it has menace. (Then planeswalk away from this phenomenon.)

Kharasha Foothills

Whenever a creature you control attacks a player, for each other opponent, you may create a token that's a copy of that creature, tapped and attacking that opponent. Exile those tokens at the beginning of the next end step.
Whenever chaos ensues, you may sacrifice any number of creatures. If you do, Kharasha Foothills deals that much damage to target creature.

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.

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.

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.

Prime Minister's Cabinet Room

At the beginning of combat on your turn, up to one target creature you control becomes a copy of target creature an opponent controls.
Will of the council — Whenever chaos ensues, starting with you, each player votes for a creature you don't control. Exile each creature with the most votes or tied for most votes.

The Matrix of Time

When you planeswalk to The Matrix of Time, each player exiles the top card of their library.
During your turn, you may play lands and cast spells from among cards exiled with The Matrix of Time.
Whenever you play a land or cast a spell from among cards exiled with The Matrix of Time, that card's owner loses 3 life and exiles the top card of their library.
Whenever chaos ensues, create two Treasure tokens.

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.