I've always found Jaheira to be a very useful tank.
Kit her out with the best armour available, Belm Scimitar or Gnasher club and the reflection shield or another good shield. I usually get her AC down to about -9 that way.
She can also cast insect plague, imho one of the best spells in the game, excellent at disrupting enemy mages and making fighters run around in a panic.
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Time is an illusion. Lunchtime doubly so.
Epona of The Laughing Hyenas