billd91
Not your screen monkey (he/him) 🇺🇦🇵🇸🏳️⚧️
For the most part, it sounds like the party wasn't really playing very smart in that encounter. I too am running that same adventure but they haven't encountered the grell yet. They've cleared out just about everything else in Jzadirune though, so they've reached 3rd level (with some close calls). I don't think the grell will be much of a problem for them, ultimately. They're a bit too mobile to just stand and wait for the grell to come to them.
Anyway, I know people like to say it was designed for 6 players, but I remember (though it may be a false memory) someone from Paizo posting that while they played a lunch game through the adventure path with 6, it was still designed as normal (it was just really hard). We had 4 PCs for much of LB and then a fifth for the Malachite Hold bit.