My tactics:

I had my paladin drink a potion of speed and proceed to throw 4x smoke powder bombs at the cluster around Kethrick's general. Think Shadowheart put Shield of faith on Jaheira? After that, Jaheira got a lay-on-hands a turn and even Sanctuary.

Karlach proved very good at jumping on rafters and throwing down enemies. Athlete feat, raging.

I think I had Gale doing Sleetstorm then Black tentacles, might've hasted someone later too.

By then, I'd have Shadowheart drink her Giant strength potion daily and play utility; healing, shoving, smacking. And of course spiritual weapon.

This is my A-team, general all round capabilities.