positioning yourself on the elevated bridges allows for an easy resolution of the encounter
Once i had the same idea ...
Sadly, some Duergars are equipped with
Arrow of Roaring Thunder.
I must admit it was really an easy and fast resolution ...
Sadly not even close to desired resolution, that would include my party being alive at the end of that encounter. :-/

@Rag! I think your account was hacked.
Dont know what do you mean.
Shove is rare example where i agree with majority around here for quite some time.

Aproximately since first few weeks in EA, when it was pointed out to me that no matter how much you try hard to avoid it, NPCs keep using it against you ... so there is no true way to ACTUALLY avoid it ...
But i must admit, i dont have strong opinion on way of fixing this ...
Either make it action, or drasticaly reduce distance, or make it lot harder roll ... either would help, all of it would be most welcomed.