The World of Avlis

Parry will NEVER parry certain attacks in a flurry (more than 1 in a round), something that really shows up in later levels but it's not always a huge problem, without it some characters might become impossible to hit unless ganged up on.

I'm guessing it's out of date 2E/BG information, if anything. It's also a very good change to the monster as you can't garuntee there's someone with suitable damage around and it means bugger all if someone has a flaming or acid weapon on them.