In the channel from Bayjin, there is a small ledge about half-way up the cliff. You can drop down to this ledge and just make out Nessie’s flank. On a whim, I stayed on this ledge and entered combat. I plinked away with ranged weapons and magic-- She (he?) stayed put. (Ranged weapons were very inaccurate at that distance) Nessie did not close to melee, and only cast 1 spell per round. Usually she would alternate between a mass-damage spell (I think it was earthquake) and a single-target spell (concussion). My party, unfortunately, seemed to be wearing down more quickly then she was; so I ended up closing and beating her at melee. However, I only have one real spellcaster. A more magical party might be able to sit on the ledge and wear Nessie down at minimal risk.