You could...reload prior to the fight.
Or quit.
I've dumped several starts and enjoyed restarting with new knowledge of storyline outcomes but yeah, the first time I accidentally laid waste to the Grove and slaughtered the teeth-lings was a bit of bummer.
This has nothing to do with OP post but it made laugh a bit.
I wonder, how does one
I accidentally laid waste to the Grove and slaughtered the teeth-lings
.

And I also do this more than I should. :p
I've dumped several starts and enjoyed restarting