Devil shades are nasty, because they can drain levels. It would help to know who's in your group, and their levels, but there are some general tactics.
1) You need an enchanted weapon. I'm not sure if +1 is enough, or if you need +2.
2) Barbarians, berzerkers, & Minsc should use their rage ability, which protects against level drain. A cleric can also cast negative plane protection on your frontliners, which does the same thing. So does the amulet of power and the upgraded mace of disruption.
3) The azureedge throwing axe from the copper coronet (after you've either freed or killed Hendak) will often destroy undead on hit, but needs a good-aligned person to use. The mace of disruption (even un-upgraded) also one-shots undead.
4) A cleric with high enough levels can chunk or dominate undead using turn undead. The success check is similar to the dispel check, basically a comparison of the casters level vs the target's levels.
EDIT wait, why is this post in roleplay? For game tips you should post in general or spoilers, if you wanted a roleplay answer you should probably give us a bit more to work with
1) You need an enchanted weapon. I'm not sure if +1 is enough, or if you need +2.
Devil Shades were in Dragomirs Tomb right? They need +2 weapons which annoyed me since I went there right after I first visited the Coronet and the only one who was damaging them was Minsc with the blade of chaos. Dragomir needs a +2 weapon too, so don't attempt Hexxat's quest if you don't have at least one +2 weapon (or enough magic to balance that out).
Comments
1) You need an enchanted weapon. I'm not sure if +1 is enough, or if you need +2.
2) Barbarians, berzerkers, & Minsc should use their rage ability, which protects against level drain. A cleric can also cast negative plane protection on your frontliners, which does the same thing. So does the amulet of power and the upgraded mace of disruption.
3) The azureedge throwing axe from the copper coronet (after you've either freed or killed Hendak) will often destroy undead on hit, but needs a good-aligned person to use. The mace of disruption (even un-upgraded) also one-shots undead.
4) A cleric with high enough levels can chunk or dominate undead using turn undead. The success check is similar to the dispel check, basically a comparison of the casters level vs the target's levels.
EDIT wait, why is this post in roleplay? For game tips you should post in general or spoilers, if you wanted a roleplay answer you should probably give us a bit more to work with
Dragomir needs a +2 weapon too, so don't attempt Hexxat's quest if you don't have at least one +2 weapon (or enough magic to balance that out).