The druids and tieflings won’t tend to come to blows as long as you go save Halsin from the goblins, and not every druid will ever be delighted to have the tieflings there, but I guess the most peaceful resolution is to:
1) Save Arabella without fighting, eg by persuading Kagha you’ll take responsibility (options vary by class)
2) Find evidence that Kagha is colluding with outside forces (find a note in a tree guarded by wood woads on an island in the swamp). You can find a note in Kagha’s chest in the back room of the druid inner sanctum that will direct you there.
3) Confront Kagha with the evidence and persuade her to renounce her treachery. Again options for doing this will vary depending on class, but I think for some it might help to have examined the plaques in the grove that show how the druids allied with Harpers to defeat Ketheric Thorm.
4) Defeat Kagha’s former allies.
I’m sure there will be more detailed walkthroughs already on the web, but hopefully that’s enough to point you in the right direction.
