¶ Overview
In 3.15 Expedition league, a new mechanic was added: Logbooks. Underground areas can be blown up and accessed using the explosives. A new fishing-related are was found: Alluring Pool.
Currently the most valuable examples are encounters in which the Fisherman "chest" drops a normal Fishing Rod. Out of dozens of examples tested at the time of this writing, we only have n=2 examples in which a normal Fishing Rod drop has occurred.
We do not yet know if these drops are "Pure RNG" or if something more interesting might be going on. (This matters because if the rod drops are not "Pure RNG", the special requirements might give us a clue or new information about other fishing secrets.)
¶ Finding the Alluring Pool
The current understanding and best chance of forcing a spawn of an Alluring Pool (as of 2/22/22) is by following these steps:
¶ The Logbook Area should be Shipwreck Reef or Scrublands
- These are the two Logbook Areas which have a maximum of 3 distinct Underground Areas. Fewer eligible Underground Areas improves the odds of seeing Alluring Pool.
- Alluring Pool may be able to be found in other Logbook Areas too -- at least according to the datamine, Battleground Graves and Karui Wargraves are also eligible areas -- but they have a maximum of 4 distinct Underground Areas which lowers the likelihood of seeing Alluring Pool.
¶ The Logbook should have "Area contains an additional Underground Area"
- We're assuming Underground Areas cannot be duplicated in an instance. Then if an instance spawns naturally with 2 Underground Areas, this modifier guarantees a 3rd Underground Area. And in the case of Shipwreck Reef or Scrublands, theoretically the 3rd Underground Area must be Alluring Pool.
¶ (Probably) The Logbook Area should be associated with Knights of the Sun
- So far 100% of all documented Alluring Pool cases were Logbook Areas with the Knights of the Sun faction. Theoretically we still might find a counterexample to this, but right now evidence indicates that Knights of the Sun is likely a requirement.
Logbooks that match all these conditions can be rare. Consider splitting ones you find, so that you have two attempts instead of one.