Return to the Fortress after obtaining Shield Transmutation at the University. Use Shield to cross the poisoned approach, reach Traverse, and light both signal fires to open the main progression gate. Captain's Key and Fortress Armoury Key open optional upgrade rooms; neither replaces the two-fire objective.
Finding the Fortress early does not mean you can complete it then. An elite enemy and the poisonous bridge stand in the way, and defeating that enemy alone does not remove the poison requirement. Continue toward Fallen Village and the main story until the relevant ability is available.
Enter from the Abandoned Church
After the University investigation, speak to Louis at the Abandoned Church and follow the objective toward the ruined castle. Take the castle route instead of continuing into Fallen Village.
Activate Shield before entering the poison and keep moving through the hazardous section to clear ground. The ability provides the protection needed for this crossing. Reaching a higher character level or defeating the entrance enemy is not a substitute for having it.
Follow the route into the fortifications and activate the Main Gate Lantern. The next important checkpoint is Traverse, in the second courtyard. Use these Lanterns and the gates you open from behind to recognize when a passage is a shortcut back, rather than a new required objective.
For the ability's pickup route rather than the Fortress itself, see Shield Transmutation location.
Light the two signal fires
The main gate near Traverse is controlled by signal fires on elevated routes. Climb the ruined structures and wooden platforms toward their towers, using the blue Nephtoglobin crossings and Grapple points that connect the walls.
At each signal, use Fire Transmutation on the wooden pyre until it ignites. Arriving on the tower or clearing its enemies does not activate the fire by itself. Follow the exterior route onward to the other tower, clearing obstructing red weak points when they block the way.
After both pyres burn, return to the opened gate near Traverse and continue into the inner castle. If the gate is still shut, check whether both signals were actually lit before searching for another key.
Immediately beyond this gate, look left for a chest containing a Quintessential Transmutation Material. This pickup is beside the required route and does not need either Fortress key.
Choose the detours that matter to you
The Fortress has several optional routes around its required path. These are useful landmarks when a locked door seems to be stopping progress:
| Area | Optional pickup or detour | How it differs from required progress |
|---|---|---|
| Main Gate | Cannon miniboss and Fire Breathing Amber | An encounter reward, not the trigger for the signal-fire gate |
| Traverse | Captain's Key door and Flask Power Upgrade | Return after finding the key below; the locked room is optional |
| Chapel passages | Fortress Armoury Key and its locked upgrade room | A separate key and a different Flask Power Upgrade |
| Chapel passages | Quintessential Blade Material in a trapped chest | A combat detour rather than the signal-fire objective |
| Courtyard | Eternal Guardsman and the body beyond him | The associated investigation belongs to The Oathbound |
For Captain's Key, use the separate key location and locked-door route. Do not confuse it with Fortress Armoury Key or the Armoury Key found in the later prison chapter.
The Courtyard investigation requires examining the body for Bastien Beaufort's Emblem and the Mysterious Stone Pyramid. Defeating the nearby guard and receiving an Amber does not replace that interaction. Follow The Oathbound guide for the wider quest.
Continue through the inner castle
Past the signal-fire gate, use Chapel, Ramparts and Courtyard as your main landmarks. Follow the higher passages and opened shortcuts when a lower route returns you to a familiar room. The area has routes that reconnect, so not every side room or locked chest is necessary to reach the boss.
The later upper route leads toward High Tower and Captain Raphael of the Nephtis Superioris. Activate the available Lanterns and finish any healing-upgrade detours you want before committing to the final encounter.
After the boss, do not rush into the next story sequence with Catalysts you intend to spend. PowerPyx specifically advises returning to the previous Lantern and leveling up before advancing: the following prison section temporarily limits access to the normal Lantern routine.
This page covers access and navigation, not an exhaustive boss move list or every collectible. PowerPyx's Chapter 9 route supports the checkpoint rewards and transition warning; Insider Gaming covers the poison gate, and the collected Fortress walkthrough describes the tower crossings.