1st encounter at the ship off the coast.
The easiest way to do this fight is to is enter stealth as you approach the 3 Intellect devourers. You want to dip your arrow in fire or use a offensive spell such as eldritch blast targeting a container to the left of the intellect devourers. This will trigger an explosion killing 1 intellect devourer and putting good damage on the second intellect devourer.
After this connects use ranged attacks then move as far away as you can each turn after combat as they move towards you until they are all killed.
This should prevent you from taking any damage and make the fight as clean as possible.
