From what I understand this blueprint can only drop from The Sentinal, does it only drop in ultimate or can that annoying son of a B drop it in elite? Currently have only one level 85 and on Ultimate he takes for ever and kills me a lot. Hoping my current level 75 plaguemancer can kill him faster once I get there.
Going for a bleed/vitality build around the death omen weapon and this helm looks to good to pass up.
Lower difficulties yield lower level variants of the Sentinel’s helm (Eldritch-Keeper’s Casque and Empowered Eldritch-Keeper’s Casque, on Normal and Elite respectively) and they come whole, whereas Eldritch Gaze only drops on Ultimate and only as a blueprint. Looks like you’re going to have to get that plaguemancer to Ult, happy hunting. 
Bummer- thanks for the input though. It’s one of maybe 7 blueprints I don’t have. I went as far as to print a checklist of all blueprints. Over 1000 hours played (I delete characters a lot, had several all the way through) but I only play Sentinal one and done for the skill point as he is typically a pain with no reward loot wise so when I read about the helm blueprint only dropping from him was not happy.
Especially since they fixed cheese killing him- run in lure him to gate (if you die) just don’t open gate and range attack though the bars a la the “Butcher” in Diablo 1.
If you want to run it I’m interested I got one of the 2 BP (didn’t learn it so I can still see it if it drop) but I still need the 2nd one and he is a pain to farm. Long and harsh
KralwCC on Steam. Mostly playing week-day during the evening (East Time Zone) so if that fit your schedule we could run it together would be faster and give us 2 chance each time we kill him to see something usefull drop.
I too play at night mostly (or in am drinking coffee if wife doesn’t care…she hates it) eastern time zone too play in the good ole state of Virginia. Can’t recall name of my sabateur (copied ultimate sabateur from “unretired” almost same gear)but pretty sure my account is also highlanderdm. If I play multiplayer I’ll name game S.GazeFarm. But still getting my plagumancer (copied plaguemancer from “Wolfoverclockedgames” all gear had)and am at the end of act one ultimate so a way till I can run hidden passage with him.
Currently therory building a Druid around primal strike and Trojan sky level 47 normal.
And a Vampire build as I’ll call it if it pans out vitality/bleed witch hunter (I had a bleeding character I made up make it to ultimate logharen but could never down him thus deleted but like bleeding skills so try two around death omen item)