The 71 new cards in the decks are set in the world of Ikoria, but the reprints can be from anywhere. There are a handful of cards from the main Ikoria set in these decks in the reprint slots, but the number is fairly small. The cards are only legal in Eternal formats like Legacy, Vintage, and Pauper.

Decklist

Planeswalker (1)

1 Chandra, Flamecaller

Creature (23)

1 Akim, the Soaring Wind
1 Brallin, Skyshark Rider
1 Shabraz, the Skyshark
1 Cryptic Trilobite
1 Herald of the Forgotten
1 Ethereal Forager
1 Agitator Ant
1 Spellpyre Phoenix
1 Surly Badgersaur
1 Eternal Dragon
1 Sun Titan
1 Curator of Mysteries
1 Nimble Obstructionist
1 Portal Mage
1 Isperia, Supreme Judge
1 Mercurial Chemister
1 Niv-Mizzet, the Firemind
1 The Locust God
1 Psychosis Crawler
1 Valiant Rescuer
1 Rooting Moloch
1 Savai Thundermane
1 Vizier of Tumbling Sands

Sorcery (8)

1 Dismantling Wave
1 Akroma's Vengeance
1 Decree of Justice
1 Descend upon the Sinful
1 Boon of the Wish-Giver
1 Windfall
1 Slice and Dice
1 Migratory Route

Instant (4)

1 Fierce Guardianship
1 Neutralize
1 Zenith Flare
1 Hieroglyphic Illumination

Artifact (10)

1 Abandoned Sarcophagus
1 Fluctuator
1 Bonder's Ornament
1 Arcane Signet
1 Azorius Signet
1 Boros Signet
1 Commander's Sphere
1 Izzet Signet
1 Sol Ring
1 Raugrin Crystal

Enchantment (14)

1 Crystalline Resonance
1 Astral Drift
1 Hoofprints of the Stag
1 Drake Haven
1 New Perspectives
1 Tectonic Reformation
1 Ominous Seas
1 Reconnaissance Mission
1 Martial Impetus
1 Psychic Impetus
1 Shiny Impetus
1 Cast Out
1 Spirit Cairn
1 Lightning Rift

Land (39)

1 Exotic Orchard
1 Hostile Desert
1 Irrigated Farmland
1 Prairie Stream
1 Shivan Reef
1 Skycloud Expanse
1 Ash Barrens
1 Azorius Chancery
1 Boros Garrison
1 Command Tower
1 Desert of the Fervent
1 Desert of the Mindful
1 Desert of the True
1 Drifting Meadow
1 Forgotten Cave
1 Izzet Boilerworks
1 Lonely Sandbar
1 Myriad Landscape
1 Mystic Monastery
1 Reliquary Tower
1 Remote Isle
1 Secluded Steppe
1 Smoldering Crater
1 Temple of the False God
5 Island
6 Mountain
4 Plains