I did this immediately after the circus quest, so it was a tough fight. I had to reload a few times before I finally beat them.
Here's what I did for my successful attempt:
1. When talking to the obnoxious dwarf, back off so that you don't trigger the fight before you are ready. I arranged my party in the room outside their bedroom. Cast all the protective spells I had (bless, defensive haarmony, chant, etc). Minsc and my kensai were at the door.
2. I got Jaheira to cast entangle (or was it Aerie casting stinking cloud? Can't remember) so that the other party would find it difficult to move around. Then I let 'em have it with spells and missile weapons.
3. Take out the imp (Pooky) first as it casts confusion - really nasty. Then go for the mage next.
4. Use Minsc and whatever tanks you have to hold off the fighters while your spellcasters concentrate on taking out the magic users, using ranged weapons and spells.
5. Once the magic users are out, it becomes a bit easier. Use whatever abilites, spells, wands you have.
Alternatively, you could come back a while later when you are more powerful. Mencar Pebblecrusher & his gang are not going anywhere.
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"Butt-kicking for goodness!" - Minsc
[This message has been edited by Hayashi (edited 05-11-2001).]