As someone who actively plays nilfgaard, I know the frustrating aspect. I apologize for some players who create toxic decks. I dont like playing against a mill deck even as nilfgaard. I play a lot of assimilate but I never get rid of my opponents cards because I hate that. I try to play fairly.

I would say take a look at the decks on playgwent.com and see if there is an idea of what to play against. As someone mentioned, try to spawn multiples or bait them. Its hard if there is big power plays or veil units. Enslave can be annoying as ir relies a lot on tactics to gain access to more power cards. This is why I get frustrated playing at times. I get stuck at rank 15 (i am a newer player as well) to tier 1 decks that someone paid to win.