Don't konw your e-mail, so I'll tell ya here:
I don't own Bauldre's Gate II -Shadows of Amn-, but I DO own Bauldre's Gate I. My best hint for killing lots of intruding beasts is to make your mage use long-range attacks, and make all of those capable use darts, crossbows, or bows/arrows to kill enemies from a distance. Only send HEAVILY ARMED people in with BIG clubs, swords, etc. into close-combat. If worst come to worst, if your mage knows some freeze or burn spells, escort him/her into battle with heavily armored guys (discribed above), and do the spells Always use caution, and pause to plan!