Hi there,
After passing 2 hours long in that lost cave, I just studied all the different ways and that's what I'm gonna share with you !
Requirements : Before going in that cave, be sure u have some revives, potions, and escape ropes.
How to understand the way : "b1f - R > b2f" => That means on "b1f" u'll have to go "R" (right) to go to "b2f" (L = Left, R= Right, U= Up, D= Down)
b1f - R > b2f
b2f - U > b3f - D > b10f (find 1 PPUp)
b3f - D > b4f
b4f - D > b5f - U > b13F (find "sea incense". U'll can farm Duskulls at night in this zone)
b5f - R > b6f
b6f - L > b7f - R > b11F (find 4 revives)
b7f - Nurse stage - D > b8f
b8f - R > b9f - L > b12f (find 1 rare candy)
b9f - L > b7f - U > b14f (GET SPINDA RARE PKM =D)
Please tell me if u have any suggestions or comments. My english not that best, so don't hesitate if I'm wrong with some words or other.
Thanks for following that guide :).