I've played BG1 in the past a few times. I remember that I generally would cruise through the entire game and then get stumped in the final battle, but that there is no way to turn back when you're finally there to get more potions/other party members/etc. Hence, I've never really finished the game. Only other fight I couldn't get through was on the lower levels of Durlag's Tower.
What's the key to the final battle? Stocking up on magic blocking potions beforehand? Specific Companions/spells? Any tips are welcome. No mods.
I'm planning to start over on a new full saga playthrough, Candlekeep to Throne (including SOD) and don't want to get stuck again.
Edit: just adding for flavour, thinking about going for a all girl Neutral(ish) party:
* CHARNAME - Shaman * Shar Teel * Jaheira (too bad I'll have to kill off Khalid) * Branwen * Imoen * Neera