- See also: Forbidden Wood
Behind the Overlord's throne in the Heavenly Keep is a "staircase" - a warp pole similar to the one that brought the party there from the top of the Yggdrasil below. Through that, they gain access to the Forbidden Wood.
The stratum is not a collection of "floors", but rather several floating islands around the flying castle. The "staircases" are really warp poles that take the party back and forth between them. But before they can explore a significant amount of it, the party must first complete a series of postgame quests involving the Foul Grail, leading up to the removal of God's Key and the defeat of the Golem. Only then will the first warp tile activate and unlock access to exploration of the rest of the stratum.
The floors bring back some of the gimmicks offered by the Claret Hollows in the previous Untold game. Vast areas of the floors are littered with giant patches of powerful damage tiles to make navigation around FOEs more difficult. Floors 28F onward begin to host warp puzzles and labyrinthine layouts. Most notably, entire rooms of the stratum have been fogged up by the Icy Bulb FOE, which not only makes visibility extremely poor to both the player and other hostile FOEs, but also hides the player's and FOE positions, forcing the player to draw out the map themselves. The final floor holds a more straightforward warp puzzle, but passing through each door on the floor will force a random encounter.
The End-bringer, the strongest monster in the Labyrinth, awaits whoever manages to brave its dangers and arrive at the deepest part of the final floor...
|26F||Mokele-mbembe, King Shroom, Gasser Tree, Ancient Hermit||Asterios, Icy Bulb||--||Crystal Vine, Forest Branch, Glow Wood, Forbidden Yuzu, Orange||--||1|
|27F||Mokele-mbembe, King Shroom, Ancient Hermit, Blood Lizard, Lord Saguaro||Asterios, Icy Bulb, Golem||--||--||Ambrosia, Forest Flower, Profound Fruit, Cauliflower, Cabbage||2|
|28F||King Shroom, Ancient Hermit, High Crawler, Black Claw||Icy Bulb, Cursed Pumpkin, Hecatoncheires*||Cat's Eye, Jade Thews, Star Rock, Bamboo Shoot, Autumn Onion||--||--||2|
|29F||Trihorn, Carbuncle, High Crawler, Moth Lord, Black Claw||Icy Bulb, Hazardous Petal||Cat's Eye, Jade Thews, Star Rock, Autumn Onion||Crystal Vine, Forest Branch, Glow Wood, Forbidden Yuzu||Ambrosia, Forest Flower, Profound Fruit, Cauliflower||3|
|30F||Trihorn, Carbuncle, Ancient Hermit, Black Claw, Moth Lord, High Crawler, Bloody Soldier, Lord Saguaro, Dinogator||Icy Bulb, Asterios, Cursed Pumpkin, Hazardous Petal, Ur-Child||Cat's Eye, Jade Thews, Star Rock, Bamboo Shoot||Crystal Vine, Forest Branch, Glow Wood, Orange||Ambrosia, Forest Flower, Profound Fruit, Cabbage||3|
*Appears once the "Shadows of the castle" has been initiated.