The Stronghold is located across the river in an old ruin and serves as the main den of the lycans, who are led by the powerful Uriaş.
This area doesn't offer much in the way of puzzles and is one of the more combat-heavy sections of the game, as you must fight your way through waves of lycans before eventually facing Uriaş as the area's boss.
First, you need to fight your way to the gate that leads into the Stronghold. Along the way, you'll encounter several lycans before reaching a small ruin with a metal gate.
To open it, pull the levers on both sides of the gate. Pulling the first lever triggers a new lycan attack, so be prepared to fight off several waves.
Once the gate is open, you can continue into the Stronghold.
Inside, you'll have a brief moment to rest and save your progress.
Walking up the stairs into the large chamber triggers a long combat sequence where you must fight off wave after wave of lycans.
The chamber has three separate floors, and you'll need to cross a wooden platform to reach the upper level.
Near the exit, you'll face a group of lycans, including an armored one.
Once you've cleared all enemies, continue through the doors.
Following the path forward leads to a circular arena where you will face Uriaș.
He may summon additional lycans during the fight, so stay aware of your surroundings.
Use the pillars to block his charges and buy yourself time.
He has a large health pool, making the fight fairly demanding.
After defeating him, head through the red door into a crystal-filled cave. Watch for small glimmers and shoot them to dislodge valuable crystals.
Weapons with high damage output are strongly recommended against Uriaș, such as the M1851 Wolfsbane or the S.T.A.K.E.
Shotguns are also very effective during the gauntlet, especially those with good damage and a large magazine size — reloading at the wrong moment can be fatal.
Explosives such as pipe bombs, mines, and the GM 79 are excellent for thinning out groups of lycans and creating breathing room.
Bring plenty of shotgun shells and magnum rounds, as the Stronghold can drain your ammo quickly.