Interesting, i killed all ghoblins and bosses in the goblin camp, execp Minthara and Saza. I saved Karga, saved mercenaries, saved Helsin, and told him, that Minthara have a plan to attack grove. But, i run away, without attaking the grove. And in the Shadow curce, i heard, than Minthara kills everyone in grove.. How??? She was alone with one ghoblin.. yes, she is 5 level, but Karga is the same level 5, and the Helsin.. It be more right, if she lose and run away.. and was panished via Ketrik... and I will found the Helsin with tifflings in Last light.
The game cannot predict ALL outcomes. It doesn't count every goblin. Only a soulless check in a code if you killed (or knocked down which is =kill for a game code check) all 3 goblin bosses.
So far a knock down is the most solid option for the devs to change code check a little. And it makes some challenge for a player.
The worst thing is that if you don't read stuff on internet - you have NO IDEA that Minthara is recruitable. It's a HUGE game design flaw. I'd make a game narrator say something like "you have a feeling that this person will have an impact in your life, maybe knocking her out instead of killing is a better option" like they have a tutorial for a knock down mechanic in the Hag's basement.