So i'm playing 36lvl Vanquisher and the game just became simulator of trying to not being killed on stairs, narrow spaces or by Dark Zealoth's instashots when you can't see them on the screen(not enought vert. Fov). I'm sure many of you guys encountered these issues and because of very repetitive gameplay they become very annoying. Not sure how are things with other classes though

I'll agree that Dark Zealots are a PITA, but I haven't really had problems seeing them. Actually, I think you can see all of the mobs before they notice you (except those that spawn). Do you have the FOV zoomed out all of the way?

For what it's worth, I deal with the zealots by using the elemental protection spell to reduce the damage they deal, and then spam whatever AoE attack I have.

Shock traps are helpful against Dark Zealots. Seeking shots are also helpful as a first attack.