So, I've decided that this will be the point where Caerth Heart-of-Oak leaves the game. Aust Thale's PC, Locke Darkmoss, will take Caerth's place in the game moving forward. With him in the fold, the PCs will still be strong enough to deal with Eike.
After the PCs meet Locke, Caerth decides that he must go back to the Temple of Bogphin and watch over it. That's his destiny. He entrusts The Hermit's personal journal to Aureus for the journey into the dark demiplane; while she cannot read it, Caerth has added some of his own notes to the book for key translations and the 'simplest' way to get to Shrine of Utter Evil. She must give it back to him once they return to the Temple of Bogphin, however.
I'm willing to have him hand over
Kang to one of the other PCs, but it's not required for the story. While the Star Arms will dislike being separated, it will be more for flavour than anything else.
Qi will take it in stride.
Cruel Justice will be upset, but as long as he knows where his 'son' is, he tolerate the separation.
Caerth absolutely insists on keeping Stratesus' staff,
Thundershadow, however.
Caerth is also going to send Screech back to Carnell with a message attached to the bird's leg telling Lady Pendour that the group is still hunting Eike and that they will hopefully return back to Carnell with Brutus's ring. He also wants to find out if there has been any word from Aeron or Lorien and will ask for Lady Pendour to send a message back to him using Screech instead of through magic.
For @Aust Thale Only!
Soon after Locke meets the PCs, Caerth takes Locke aside and tells him that the journal has a passage in it that might refer to Locke's arrival in the region. He's not sure. It is cryptic and the journal is written in Druidic, so only Caerth can truly read it. Once the PCs return to the Temple of Bogphin, he will try to decipher the passage and tell Locke more.