Just beat this fight with a level 10 Party of my Rogue, Eder, Pallegina, Hiravias and Grieving Mother. Took "only" four or five tries. Might have been easier with Sagani instead ot the latter.
I sent in Eder aloneto initiate the fight and while he was retreating I blocked of the stairs with summons: The scarab, the shades and the wood beetles.
Then I bombed them with Fireballs and missiles from Aloth lightning from Hiravias.
It was still close with only Eder and Pallegina still standing, but in the end he killed himself with a fireball.
