There are a handful of things I know for sure; one, Icewind Dale is cold. Two, dragons horde treasure. *Chuckles* Sneak past…ha!
Morentherene has poison attacks and is extremely susceptible to fire. On core rules the fight was a piece of cake once I buffed my tank with Protection From Fire spells, then unloaded fireballs, Wand of the Heavens, Arrow of Fire +2, and anything else that remotely looked like fire.
If you take the same approach, you’ll meet little resistance. Now about that dragon’s horde…(13000 xp, Dragon Scales, Morentherene’s horde: 3000 gold, Emerald x3, Diamond x2, Star Sapphire, King’s Tears).
If you chose to sneak past Morentherene, move onward to the Bugbear Caverns.