Guides → Boss guide
Boss guide and major combat encounters
Major gameplay and ending spoilers. The game reuses elite enemies such as Deep Ones and Acheronians, so this page separates repeatable elite encounters from the two large late-game mechanism/final-boss fights.
Major fights at a glance
| Encounter | Core solution | Main risk |
|---|---|---|
| Acheronian | Keep space, punish exposed growths and do not trade hits. | Its reach closes narrow rooms quickly. |
| Shadow | Use damage to force it away; some story encounters are survival/banishment phases. | Wasting all ammunition on a threat that is not permanently killable yet. |
| Deep One | Shoot the legs to force a kneel, then target the growths on its back. | Focusing the body while adds or terrain cut off the escape route. |
| Shoggoth | Activate all three arena devices, then shoot the exposed eyes; repeat. | Trying to damage it before completing the device cycle. |
| Slither Prime | Keep moving, clear summoned enemies and return fire to the glowing head. | Being surrounded while tunnel-visioning the boss. |
| Ezra & Shadow (DLC) | Manage the Shadow pressure while completing the final Holloway Manor combat phase. | Entering the lower-manor route without healing or reserve ammunition. |
How to beat Shoggoth
- Use the safe room at the bottom of the stairs before dropping into the arena.
- Locate and activate all three strange devices while staying mobile.
- When the eyes are exposed, concentrate accurate weapon fire on them.
- Repeat the device-and-eye cycle; its pressure increases after each damage phase.
The arena mechanic is mandatory. Shooting the body before the eyes are exposed spends ammunition without advancing the fight.
How to beat Slither Prime
- Craft and load ammunition at the final safe area before opening the large door.
- Aim at the glowing head whenever the firing lane is clear.
- Break off damage to remove summoned enemies before they surround Calvin.
- Dodge across open space, reload only after creating distance, then resume head damage.
After it falls, walk with Faye to the altar. For the surrounding route, use the full walkthrough.
Boss-fight video (base game + Holloway Manor)
Strategies cross-checked August 20, 2026 against the complete GameSpew route and the embedded launch-build boss compilation. Enemy labels vary between community videos; this guide uses the names shown by the walkthrough/achievement context and describes mechanics so the encounter remains identifiable.