In lore as far as I know, drows can and do end up getting captured.
Yup ... and they strugle to their last breath, since they know better than anyone what is happening to prisoners, or slaves.
I feel like I have used the wrong word to describe it; it should look somewheat like this:
Her henchmen are dead/fleeing and she is at low health, (let's say below 35% of maximum), with enemies surrounding her. A cutscene triggers, during which she falls on her knees, visibly wounded and exhausted. You are given an option to approach her, with several options possible:
a)Finish her off
b)Give her to tieflings
c)Take her as your prisoner
I see no need for this cutscene ... we either finish her off in regular combat, or knock her out ...
And if we knock her out, then Zevlor (and possibly Halsin) asks us after battle, what will we do with her ... then we can decide to either give her to tieflings, or druids, or keep her for oureself.
I simply dont like the idea her showing us her weakness.

Here we should be able to choose, what to tell her, for example when roleplaying lawful good -> "There will be no harm done towards you from our side", lawful evil - "Show that you are useful and you might still live"
So I just meant that she surrenders due to her inability to fight or do anything basically, not straight begging for mercy.
Minthara is shown to both value her life very highly and to be cowardly, so there is a reason why she would surrender.
As for resurrecting, certainly that should be a + in relation if player is willing to try to redeem her. If we end up killing her, I know that in Forgotten Realms characters have to agree to resurrection; so this could be tricked by forcing someone else, like a goblin mage/priest/warlock to read the scroll. After which a big suprise moment happens for Minthara.
This whole conversation can be just the same happening in your camp, when she is in that cage ...
After all, she have informations we could want.
I based this on indication, that she is not exactly 100% loyal to the Absolute, which is given during dialogue with her in a Camp. Since Minthara can't really return back and she has enemies everywhere now, the drow might decide to do anything to improve her dire situation. It could be done in a different way, like she reveals to you only basic and unimportant information, since there is little trust towards but it improves as time goes, if you continue to act well towards her.
Just like the rest of Absolute leaders, she doesn't show an awarness of being infected by the Tadpole too, so your point with Moonrise towers is great and could give her a good reason to reconsider what is she doing and let her for example join us as a companion in act 2.
And that is exactly why i would pass every relation mading decision to post-moonrise towers ...
First of all, seeing on her own eyes what is happening there could shaken her believes.
And also (as much i presume) in the end of Moonrise Towers story your character will probably be known either as blessed by the Absolute ... or destroyer of the Absolute ... so, that sounds to me like good reason for Minthara to concider you either valuable aly, or threat big enough to want to stay on your good side.
Yes, mocking our character definitely fits her, although it's shouldn't be to the point of it being ridiculous since she is not stupid and her situation isn't exactly the best. And if you continue to treat her humanely for long enough (by for example giving her normal food and drink instead of just bread and water, letting her sleep on bedroll instead of sleeping on the ground, letting her keep the equipment (except the weapon and shield obviously, bandaging her after the fight, bringing her a health potion), she should behave better.
I imagine it as mocking and laughting at us for the first time ... and in time change that to lecturing us about how people need to be strong, and how our good will and hope makes us weak ... then there could be some persuation dices to show her that even in our "weakened" status we were able to defeat her ... etc. etc.
Basicly i believe that Minthara in cage is perfect opourtunity for our protagonist to lead filosofic debates abour selflessness vs. selfishness, pros and cons, etc.

First time, when you ask her when she is your prisoner, how is she feeling? You get a insulting response in a style of "go away and see if you aren't somewhere close to that rock nearby"
But when enough time passes and you don't stop treating her well, she will respond first neutrally, then nicely. At one point she will say, that if you let her join your squad, she will be a much more useful than just sitting here in the prisoner cage doing nothing.
Same reaction as abowe, and even more abowe.

It is shown if you side with her, that she is definitely someone with a huge logical possibility of redemption arc, with it starting to get going after we reach Moonrise Towers in act 1 and with act 2 letting us recruit her as a companion.
Honestly, i hope not.
Yes, there certainly is possibility for redemption arc, and i think that would be shame (or misstake if that would be the only way) ... not everyone in world need to be redempted, no everyone want to be redempted, and since some protagonist simply are evil, they also need someone to follow them.
Anyway why so many people loves redemtion story, and we get so few coruption story?

It could be fun if in every single conversation between Minthara and Protagonist we have options to either try to redempt her, or being corupted by her ... and see where it goes. :3
I dont see any conection between Halsin and Tieflings ...
So why this condition? O_o
Because he seems to be a good person caring for the rest and unlike Kagha he does show a soft side for Tieflings by letting them stay in the Grove.
Maybe ...
I know that in mine first gameplay i decided to help tieflings, and killed Kagha ... and every single other druid with her ... and truth is that Halsin forgived me, with words "you did what you had to do" ...
But anyway this condition still seem odd ...
We should be able to tell, and show "captured Halsin" all things we can no matter if we killed Tieflings or not. :-/
Even if we wipe whole groove ... we can regred that decision afterwards, especialy if we then also fail to persuate Minthara to not attack us, since in that case, we are litteraly alone.
Since using secret passage will have same result, and since you are no "suply manager" of the groove, but simply traveler, who just happened to arive there ...
I cant quite imagine how exactly you like to justify such action. O_o
Zevlor mentions using oil barrels as a part of defense plan and tieflings trust you in 100% when you side with them during the first attack on grove.
Yeah, they were diging holes and filling them with oil barels since you left (unless you decide to return, before you tell Minthara where they are) ...
It just still seem odd ... like:
"Heya Zevlor, things just happened and i have found this 20 barrels of
certainly 100% oil, dont open it even if they weight barely half of those you have ben diging all around whole afternoon ... wanna use them aswell?"
Sorry, but i cant see it right, especialy if using secret passage gets the same result without need of your "simple traveler" become bigest oil merchant in sword coast. :-/
I remember seeing survey on reddit, with players being asked what could make them play the evil side. Suprisingly.... it was "better story reason"
I have not seen any survey, but i have participated in many discusions on this theme with other people here on forum ...
All i can say for sure is that some will never be satisfied. And not even Larian can please everyone. :-/