afaik most boss fights have an autosave on initialization.
when she talk you can at any point in the conversation:
-examine her with other party members
-move other party members (including running away)
-teleport her away
the fist thing you should do when facing bosses is spread your party, to avoid aoe damage, in that regard she is a fair boss. the lvl 18 troll can oneshot your whole party and you have a much harder time spacing your party on the narrow bridge.
when i read your posts i conclude that:
-there is information lacking on how powerful her opening is -> introduce game lore, so an attentive player has knowledge. however there are a lot of corpses that should tell you: warning dangerous boss ahead.
-the game should maybe teach you more about what your options are, again unless you close the dialog you can still run away with 3 out of your 4 party members, or drink fire resistance potion or at least space out your party
i like a game where you have side-content that actually is difficult and even if you don't know the boss there are many things you could have done.
i really disagree with the notion that you should be able to walk into the hardest optional bosses unprepared and come away victorious.
In a game offering the player to play honor mode just like diablo 3 hardcore, you're not suppose to implement this kind of behavior into a game where you would simply loose instantly by standing in the wrong place
try path of exile hardcore, this game has a lot more unforgiving mechanics and content than all of dos2. again: even if you are locked in the conversation with her you can:
-examine her for weaknesses and strengths
-move you characters (the ones who are not in the conversation)
-analyse the battlefield
you don't have any time pressure, nobody forces your party in that encounter to stand together so all can die from the initial fire ball. you are not forced to fight her in the fire, you are not forced to deal with the totems, you have a lot of options that you could have taken to prevent a party wipe.
