Project Slayers 2: All Serpent Keys Locations for the Nightfall Serpent Katana

The Serpent Key hunt in Project Slayers 2 is the gate standing between you and the Nightfall Serpent Katana schematic. Keys sit on the seabed all around Mistfall Harbor and the surrounding wilderness water, and only one of them opens the locked chest hidden in the cave at Verdant Cliffs. The catch is that the working key is rolled per character, so knowing every spawn point is the whole job.

Quick answer: Buy an Underwater Breathing Potion from Alchemist Meku, then sweep the roughly 20 Serpent Key spawns around Mistfall Harbor and the wilderness water, testing each key on the Verdant Cliffs chest until one opens it.

What you need before diving for Serpent Keys

You cannot hold your breath long enough to clear a full sweep without help. Alchemist Meku stands on the Mistfall Harbor dock and sells the potion you need.

• Underwater Breathing Potion from Alchemist Meku at the Mistfall Harbor dock, for 6 Demon Horns and $600.
• A mount or fast travel access, since several keys sit far out toward the cliff boundary.
• Free inventory room, because you will pick up multiple keys before one works.
• The cave at Verdant Cliffs marked on your route, since every key has to be carried back there.

All Serpent Key locations in Project Slayers 2

Keys lie loose on the sand and are picked up with the interact prompt. The list below runs in the order that makes for the shortest swim, starting at the harbor dock and working outward toward the wilderness cliffs.

The first stretch is the densest. Dive straight off the harbor dock, hug the wall foundation for the first two keys, then follow the seabed outward and keep your camera angled down — key 3 sits in open sand along that path with nothing nearby to mark it.

01:06Serpent Key 3

Keys 5 through 8 cluster around the mill. Surface briefly near the water mill for key 5, then swim past the row of submerged pillars and along the base of the water wheel. Key 8 is tucked into the corner where the map’s wall boundary meets the seabed, which is easy to swim straight past.

02:28Serpent Key 6

Two spawns hide in the dock structure itself. Key 9 sits inside the wooden cage bars underneath the pier, so you have to swim between the slats to reach the prompt. Key 20 is under the same pier area and is the one most players forget, so check it before you assume you have swept the harbor.

04:02Serpent Key 9

The remaining keys are spread across the wilderness water. Swim out toward the cliff boundary for key 10, then follow the rock walls and metal grates for key 11. The cluster of 12, 13 and 14 sits together on flat seabed, 15 and 16 are down in the deep trench, and 17 through 19 run along the shore bed, the cliff base and a raised underwater plateau.

How to use Serpent Keys at the Verdant Cliffs chest

Collecting keys does nothing on its own. Each one has to be carried to the locked chest inside the cave near the village at Verdant Cliffs and tried there.

You will know it worked when the chest unlocks and the Nightfall Serpent Katana Schematic appears in your Inventory. That item is the confirmation — no quest text or marker is needed.

Crafting requirements for the Nightfall Serpent Katana

The schematic is only half of the recipe. You still need the V2 katana itself, which is forged in the Dungeon area after Blacksmith Togane in Hidden Mist Village points you toward his second forge in Ouwigahara. The route runs from the Mistfall Harbor Shrine, past Rengoku in the Forgotten Ruins and across the long stone bridge through the torii gates to the purple dungeon portal, and you generally want to be around level 65 before attempting it.

03:22V3 Weapon Crafting Overview

Dungeon Points come from runs inside the dungeon, and floors 60 to 70 will usually clear the 90,000 threshold. Metal Scraps and Silk Thread drop from chests. Mythic Refinement Ore can be bought from Changer Zeni for 30,000 points each, or salvaged far more cheaply by taking Mythic-rarity gear to Ginzo near Mistfall Harbor, who returns one ore per item.

Each V3 weapon has its own schematic hidden somewhere on the map, so the Serpent Key route only unlocks the katana — the Stone Breathing Nightfall schematic, for example, sits on a frozen altar in the rafters of the Bamboo Grove pagoda above Hidden Mist Village.

08:14Nightfall Stone Weapon Schematic Location

Nightfall Katana stats and weapon class

The finished katana is a Duelist weapon, which pushes damage over defense. The Firstlight Katana, found in the Iceveil Valley cavern, is the Sentinel alternative and trades raw damage for blocking.

11:56Katana Stat Comparison

Because the working key is rolled per character, the honest expectation is several full laps of the harbor before the chest opens. Buy a stack of Underwater Breathing Potions, clear the dock and mill spawns in one dive, and only head to Verdant Cliffs once your inventory is full of keys to burn through.