In this case, I’m talking about the unique spear " Sierpin’s Fractal Tree". It seems like it’s bug. 4 heroes were leveled up to about level 80 this season, about 80 exaltation runes were spent, a lot of predictions, there’s even an imprint in the weaver tree. All the other spears fall in dozens, but this spear is somehow cursed. In 2 weeks of playing, only one fell and that’s it.
Please, check if the drop chance of this item is correct.
None of the methods you listed mean anything when grinding for that particular spear. The Sierpin’s Fractal Tree only drops from exiled mage encounters:
https://www.lastepochtools.com/db/items/UAzAsGYCZiA
It cannot drop from tree imprint, from ascension runes, or predictions.
Leveling 4 character to 80 was not productive in grinding for this spear as it’s drop chance increases with corruption level and area level.
This is not a bug