If you're missing a miniboss or a perk.

[Asmund]

You have to fight the mask boss under the bridge in the left zone to get a perk that only he can drop (I was missing his) all other perks can drop from treasure caches (looks like a giant spider egg, and for the miniboss in the right zone on the very extreme far right of the map you practically have to leap of faith dash to some land over there to find it.

Here's an updated map (the google drive one from reddit is old and some stuff has been moved around)
https://cvex2150j.github.io/SunderedMaps/

Edited April 24 by Asmund