Reach Beachside Pier → Visit Small Harbor 2 times? (Unconfirmed)
Entrance
Small Harbor (From the docks).
Floors
7F (Blue stairs from 4F)
Bring Items
Yes
Stairs
Varies
Companions
Roamers
Yes
Rescues
0
Starting Level
Continued
Starting Item
None
Unidentified
Bracelets, Pots
Shops
No
Monster Houses
Yes (Sudden)
Behemoths
No
Wishing Shrines
No
Kron's Challenge
No
Fever Time
No
Initial Enemies
4~6
Spawn Rate
30 Turns
Wind (1st Gust)
1200 Turns
Reward
None
Hidden route that unlocks when you've reached Beachside Pier once and visit Small Harbor twice? The floor numbers are displayed as 1-7F, but the dungeon corresponds to 10-15F of Serpentcoil Island. Blue stairs which let you return to regular Serpentcoil Island floors early can be found starting on 4F. Once unlocked, this dungeon can be entered anytime.
The main characteristic of this dungeon is that Behemoth Gates can occur on all floors. In addition, only monsters with swift action speed spawn between 1-4F, so retreating is ineffective. This means you'll need a shield strong enough to withstand Karakuroid and Hell Reaper's attacks. That said, Karakuroid has 20 attack and Hell Reaper has 12 attack, so the requirement isn't very high. Otherwise, the only other monster that spawns is Bowboy between 5-7F, so it's not too bad.
Overall, this dungeon is mostly pointless, since shops don't spawn and you miss out on a blacksmith. The only real benefit is that Blue Sacred or Golden Sacred items can occasionally be found. Lastly, don't forget that rescues are not allowed in hidden routes.
Floor Guide
1-7F
Behemoth Gates have a chance of being generated on all floors. Beware of Behemoth Pumphantasms in particular, since they can pass through walls. 1 Rock or Porky's Rock is enough to one-shot them from any direction, as rocks arc over their barrier. Rocks will still hit monsters that are inside walls, provided you have the proper line of sight.
Karakuroid (1-7F) has Swift 1 speed, meaning it moves 2 times per turn but only attacks 1 time. It's always generated with Napping status, and always wakes up when you enter or exit the room. It also has the ability to create traps, and stops acting for 2 turns after doing so.
Hell Reaper (1-7F) has Swift 2 speed, meaning it does any 2 actions per turn, including attacking twice. This monster doesn't hit very hard, though, so you should be fine if you have a half-decent shield.
Bowboy (5-7F) shoots Wooden Arrows from up to 10 tiles away in a straight line. Bowboy can be used to collect arrows if you have an Earthmound Staff or Evasive Incense, but don't attempt any farming techniques until you've made the Behemoth Gate vanish first. A Behemoth Gate vanishes and leaves behind an item once you've entered every room on the floor.
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Karakuroid
Hell Reaper
Bowboy
Chintala
Pumphantasm
Shagga
Weapon
Shield
Bracelet
Projectile
Food
Grass
Scroll
Staff
Pot
Incense