Can't remember who it was who posted the topic, but these guys are not Physically Immune even tho it states they are. My merc is killing them rather quickly on p8 and the only elemental damage he has is 75 poison damage from Insight. I tried it without OW, CB and ANY elemental damage, but the results are the same.
How it works if they are Stone Skin? They will probably go over 100 physical res, but with Amp on them aswell? Not sure! Gotta test it if I get my hands on Amp!
Level 3 wasn't horrible either.
Level 4 was quite slow and a lot of monsters in the way. Not the best map but I do "only" need Lem.