iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
The three reported optional-boss locations in End of Abyss are the drained Reactor Pool, the upper Ventilation Tunnels, and Infirmary B1. Each requires an access route or unlock step before the fight: drain the Reactor Pool for the Centipede rematch, open the upper tunnels to reach the Brood Keeper, and unlock the Infirmary to find the Morgue Dweller.
Optional boss locations at a glance
| Encounter | Location | Main access requirement | Reported reward |
|---|---|---|---|
| Centipede rematch | Drained Reactor Pool | Complete the Waterworks B3 drain sequence, then return to the Reactor | Vault Key #6 |
| Brood Keeper | Upper Ventilation Tunnels | Enter from Factory East; use an Explosive Charge, Ventilation Maintenance Key, Grappling Hook, and switch | Vault Key #7 |
| Morgue Dweller | Infirmary B1 | Unlock the Infirmary from the Lower Levels, then obtain a Restricted Access Keycard inside | Vault Key #8 |
The locations, routes, and Vault Key numbers are reported by third-party guides, including TheGamer’s boss-location guide and Game8’s End of Abyss guide. The game’s developer or publisher has not been cited here as confirming these details.
Where to find the Centipede rematch
Drain the Reactor Pool first
The rematch takes place in the Reactor Pool after it has been drained. The route reported by TheGamer runs through Waterworks B3:
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware match- Use the Grappling Hook to reach and activate the wall switch.
- Activate the switch beside the circular structure.
- Operate the pump console on the east side.
- Use an Explosive Charge to clear the blocked wall.
- Follow the upper-right route to reach and activate the final switch.
Return to the Reactor
Once the pool is drained, go back to the Reactor and climb down into the pool to trigger the rematch. The encounter is described in guides as “Husk Centipede” or “Centipede Husk”; the name “Severed Husk Centipede” is not consistent across those guides. The reported reward is Vault Key #6.
Where to find the Brood Keeper
Reach the upper Ventilation Tunnels
Enter the Ventilation Tunnels from Factory East. The route reported by TheGamer and Game Rant requires an Explosive Charge, a Ventilation Maintenance Key, and a Grappling Hook:
- Use an Explosive Charge on the weak wall near the easternmost entrance.
- Go through F2 into F3. Defeat the ambush there and collect the Ventilation Maintenance Key.
- Return to the lower-left area of F3 and use the Grappling Hook to lower a ladder.
- Use the key to open the door, then activate the switch.
- Return to F1 and climb the ladder in the circular room to reach the Brood Keeper.
The guides report that the Brood Keeper awards Vault Key #7.
Rank #2
- FACE THE LEVIATHANS: Adds a new Border Board and Leviathan cards to replace the threat track, introducing sea monster battles that add tension and excitement to every game.
- NEW LORDS AND ALLIES: Recruit powerful Lords and Allies with abilities designed to help you fight Leviathans and secure victory.
- GAIN EXTRA REWARDS: Defeat the most Leviathans to earn the statue token and gain 5 extra victory points at the end of the game.
- HIGH STAKES AND STRATEGY: Explore the depths carefully—fighting Leviathans is risky but rewarding, while fleeing may result in injury.
- EXPAND YOUR ABYSS EXPERIENCE: Requires the Abyss board game to play. Designed for 2-4 players, ages 14+, this expansion deepens strategy and gameplay.
Where to find the Morgue Dweller
Unlock the Infirmary
In the Lower Levels, burn a Parasitic Spire with the Incinerator to obtain the Infirmary Key. Then take the lift near the Habitation Sector shuttle to enter the Infirmary.
Recommended Free Tools
Go down to Infirmary B1
On F1, collect a Restricted Access Keycard and use it to open the route to B1. The Morgue Dweller is on the right side of B1. The guides report Vault Key #8 as the reward.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which route should you tackle first?
The available guides establish the access steps but do not recommend an order or compare the fights’ difficulty. Choose based on the areas and traversal tools you already have available:
- Reactor Pool: choose this route if you can complete the Waterworks drain sequence; it uses the Grappling Hook and an Explosive Charge.
- Brood Keeper: choose this route if Factory East and the Ventilation Tunnels are accessible and you can obtain the maintenance key.
- Morgue Dweller: choose this route if you have the Incinerator for the Parasitic Spire and can reach the Lower Levels and Infirmary.
Third-party guides describe these three fights as the sources of Vault Keys #6, #7, and #8, completing an eight-key set. Treat the reward numbering as guide-reported rather than officially verified.
Quick Recap
Best Value
- Intensive tactical confrontation: Take control of your legions and dominate the most important places of the kingdom.
- Strategic game for 2 players: each choice affects morality, initiative and zone control.
- ABYSS WORLD - Discover the unique atmosphere and beautiful illustrations of the Abyss-Saga.
- Created by renowned authors - Bruno Cathala, Charles Chevallier and Johannes Goupy unite their talent into a captivating duel.
- Ideal gift for strategy lovers: a compact, rich and immersive game, perfect for parties as a couple.
Rank #4
- For 1-6 Players. 60-90 minute playing time
- The Assault Units, the Krohns, will advance towards Zone 1, and once there, they'll attack the Heroes on the wall and try to break into the Citadel
- Gargohs, the Support Units, will advance towards Zone 2 and, once there, they'll hit all Heroes in the Quarter they face
- Molens, the Heavy Units, will attack directly from Zone 3 and damage all Heroes and buildings in the Quarter they face
- Each monster figure on the board will activate and perform their actions according to its rank. The Heroes must coordinate their actions well to share resources
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
