I was farming various substances in Hollowshade Moor and killed the Screechmaw. 2 Discordant Mind nukes and about 15 seconds of dancing with my 49th level pet and he was done.
He dropped an ac19 4wis some hp and other statted bp that fit plate classes and monks for some reason... weight 8lbs. Sinue wrapped Owlbear ribcage or some sort. as stated already, was in the chiefs spot and bites pretty hard.
I killed him last night with my 49 druid. the owlbears had taken the grimling camp and he spawned where normally the chief would do. he is a bit tougher than i thought cause he nearly cant be rooted. even snaring is often resisted. my starfire and ice nukes were not doing the full damage most of the time and sometimes even resisted. i kited him along the wall. first kill i got nothing, but second kill he dropped a Feathered Owlbear Mantle Magic Lore Shoulder AC 4 WIS 4 INT 4 SV Fire,Cold,Poisen 2