The fight in the Last Light was really tough when I attempted it; Isobel will heal herself but she has to survive until her turn to be able to do that, I too needed a second attempt because my party was very poorly positioned when initiative was rolled so I just couldn't help her enough in the first round.
It's one of the big problems in BG3 compared to actual D&D; firstly BG3 has a habit of throwing enemies at you that are every bit as strong as your own party, but there's always more than four of them, so action economy is usually against you, even with allies. This makes many fights tough as nails even on "balanced" difficulty, unless you know what to expect. So going back to a save game for a do-over is very much a legitimate strategy, because far too often I've been ambushed only to watch helplessly as my party members are bonus action shoved to instant deaths or other BS like stun blasts during a surprise round etc. that your average DM wouldn't pull on you.
This isn't helped by the fact that uncontrollable allies in BG3 are completely suicidal.
In Act 2:
Jaheira is another one I had to go back to a previous save over when attacking Moonrise towers, because I had Wyll cast Hungry Hungry Hadar (Hunger of Hadar) for some immediate control/area damage, but Jaheira just ran straight into it to get surrounded by the toughest group of enemies in there and immediately killed. Fortunately my Gale had learned Otiluke's Resilient Sphere, so when I tried again I wrapped her up in an invincible hamster ball and got stuck in (having lost a round of fireball thanks to her), and I'm glad I did because she is such an important NPC in Act 3 (you'll miss out on some of the best content in that act without her).
In Act 3:
There's a similar problem when you go to the Steel Watch Foundry; saving the Gondians is near impossible without preparing specifically for it (lasts of haste effects, maybe dimension door so you can save them from themselves), because they seem determined to get themselves killed. One who had already been hit twice by steel watchers actually misty stepped in order to chase one of them, moving himself away from any hope of being healed, then when I miraculously managed to bring it down he decided that maybe the giant red circle of death indicating an imminent self-destruct seemed a lovely spot to plant himself so he could be blasted into a pile of mush. I mean WTF?
Unless there are some major allied AI improvements coming to help them behave like they actually
want to be alive, it would be better if allied NPCs were put under player control; those that are recruited by speaking to them should be given to whoever spoke to them, anyone rolled in randomly should be distributed evenly.
