This whole paragraph is a little comedic to me because you make it seem like without Minthara, the evil path would be essentially nothing. I had hopes they would give us Nere, Sazza, or even Z’rell as a companion. But then I realize their writing might be rushed like Karlach, or watered down/changed entirely like Halsin. The companions we currently have also leave a lot of room for improvement. I’d agree to making it so we can sway Wyll and Karlach to being evil, but their moral codes are already pretty strong. I personally just can’t see much that can be done without altering the entire game. Maybe they’ll do an overhaul for DE, maybe not.
Because at the moment it is. Without Minthara, the evil path is nothing. It does not give you any content, no companions or personal evil quests. And the only reason for many players to destroy the grove at least once is Minthara. How do I keep Minthara from getting more content? Let them add more personal quests to her, on evil path. In any case, you will only recruit her in the second act. In a good path or an evil one, she will not have any more personal content from this. So I do not know how you combined "add more content to Minthara" and "add Minthara to a good path".
