Unspeakable World (語られざる世界, Katararezaru Sekai lit. The Untold World in the Japanese version) is Chapter 7 of Fire Emblem Fates in the Revelation Version. This chapter takes place in the Canyon Valley.
The script for this chapter can be found here.
This map superficially resembles conventional fog of war maps, but in practice it functions a bit differently. Notably, the enemy units here won't move until they come into view, making this chapter more a matter of cautious exploration than anything else, almost akin to a conventional roguelike. Corrin should take the lead, as he/she should be the most durable unit of the trio, and could use the EXP. When Corrin steps into the darkness, one of two things might happen.
- The next room will reveal itself along with 3-5 non-magic ground units. Or...
- The unit you sent down the hallway will teleport back to the centre of the last room they were in.
The map provides a subtle visual cue as to which paths will lead to which outcome: if you see a thicket near the darkness, a teleporter lies dead ahead.
If you stumble upon a teleporter anyway, have Azura sing for Corrin to refresh his or her energy and get him or her to go the other way. Once you enter the second-to-last room, Gunter will appear and join your cause.
There are actually two separate paths the player can take to get to the boss's room. All six treasure chests are split between them, so the player will need to backtrack after clearing out one path to go on the other. Both paths lead to the room Gunter is met in, so there is no "correct" path. Have your Avatar keep the Dragonstone equipped and be paired with your servant at all times, as no unit should be capable of doubling him unless you chose a speed bane. If male, Felicia proves especially valuable since her personal will lower the damage Corrin takes, though in cases where the enemy is made up of archers, you do need to be careful with her. If Female, Jakob's personal will let you avoid numerous attacks. Either way, getting a C pairing with them beforehand is recommended.
The map, even on Lunatic, is not particularly challenging. You simply need to be wary of the enemies and prevent them from ganging up on you via strategic use of the chokepoints that litter the map. Be sure to always let your servant be nearby if Corrin needs healing.
The boss is completely stationary and cannot attack at range, so you do not actually need to rely on Gunter to take it down. Even Felicia, who normally has terrible Strength growths, can prove useful in debuffing the boss and chipping him down. If you are patient, you can score a crit on the boss using the Killing edge and get his HP down much more before simply sending in Corrin for the by then easy kill.
- Chest Key x6
- In this chapter, there are 4 slots to deploy units, while there are only 3 units which can be recruited as of this point in the game without using DLC (Corrin, Felicia/Jakob, and Azura). Presumably, this extra slot is to be used for units such as Amiibo or units from the Logbook such as previously captured units from prior playthroughs. It could also be that that Mozu was intended to be recruited beforehand.
- This is the only route where Silas does not appear or join in Chapter 7 of a path.