I can stagger perfectly berserkers by pushing them to the ground… Plague monks i cant… Why?
Wouldn’t be surprised if they were exempt by lore xD.
“Ah, yes. The Plague Monks. Where to begin? These wretched creatures have wholly embraced the diseased aspect of their horned god. They inflict themselves with sickness, drawing strength from it and gaining some measure of immunity to mundane diseases. So inured are they to pain and discomfort that they hardly feel it any longer. Driven by a fury and zeal that only the truly religious can comprehend, the Plague Monks are certainly one of the Skaven’s most disturbing and terrible innovations”
What? So you’re implying, that plaguemonks can be staggered? 
They do get staggered by everything else though. This goes hand in hand with what I was getting at before about how the flamewave stagger is busted weak relative to how it should be.
Berserker and monks are notoriously hard to stagger on legend, not even fireball staff does it completely reliably; you have to read their movements constantly.
I think a root issue is more that if they’ve started an attack chain they will be very difficult to interrupt. This is noticeable for stealth characters primarily, they will pursue you through their whole attack chain while you are in stealth.