I went through the first intellect devourer fight and as a DM I think this fight is a bit out of line. The player has two characters who will have around 8-10 HP on the average and the IDs will do enough to kill one of them in two blows. Ranged fire is unreliable, I generally do no more than 3 points of damage with a bow. I beat the fight by running a cleric alongside Blackheart with both using shield of faith and guiding bolt, options that I think surpass what most characters have available at that point in the game.
It's an odd fight because the best solution is kiting:
01. Rogue, Ranger, and Fighter all have access to Short Bows, and the fire to dip for flame arrows for the first one or two shots.
02. If your Rogue, Ranger or Fighter have two weapons they can fight with, then they can swap to dual wielding when the Intellect Devourers get close, after kiting them for a bit.
03. Cleric, Warlock, and Wizard all have long distance cantrips that do a lot of damage, so you don't have to dip into spells too much.
04. Cleric, Warlock, and Wizard all have long distance spells which do even more, and/or comparable damage to cantrips. depending on what you chose.
05. Wood Elf and Wood Half-Elf characters also have a slight advantage in this first fight because they get extra movement to make sure they kite a bit more effectively.
I actually like this first fight. It's more about thinking about problem solving than just running into it blind, As a massive fan of the first games, most of the best early fights in BG1 in particular were similar. You needed to be a bit cautious without any gear at a low level. And Ranged Weapons (as with real D&D), and Cantrips/Spells are more advantageous to use at the start of a game.
I got lucky and found two Short Swords with my Wood Elf Rogue on the ship before it crashed, so he was able to dip in the fire, shoot twice to kill one, and then swap to two short swords to kill a second weakened Intellect Devourer by himself.
Whereas with my Wood Half-Elf Warlock, it was all about Eldritch Blast (no need really for anything else, as I didn't even have to cast Hex).
I'm going to be building most of the possible characters (while taking notes), but aside from an Intellect Devourer getting a lucky Crit, you should be able to kill them with some combination of kiting and melee fairly easily (no matter what class of character you create).
