One thing I am still wondering about is why the hell did Halsin trust in us, a bunch of tadpoled 'misfits' to be able to heal the land from the shadow curse. From what I understood, even a good amount of druids and harpers didn't stand a chance. But then again, I think it could just Halsin being so desperate that he takes every chance he can get.
This is what I concluded. Hes kidnapped by the goblins, he hears them all talk about The Absolute and Moonrise. He thinks holy crap what are these wierdos doing at Moonrise? He sees them sending people to and from Moonrise as well. He has a personal stake in whats going on. Its an oppourtunity 100+ years in the making. He meets us, hes somewhat familiar with the tadpoles, sees the connection between our tadpoles, the cult, and Moonrise. Its an oppourtunity for him to make progress he wasnt able to make before. The tadpole thing and the cult are relatively new developments and he goes along with it because he wants to lift the shadow curse. He sees we wabt to be RID of the tadpoles and helps us because we can help him. Its a mutual agreement with mutual benefits.
The shadow cursed lands are his childhood home. Hes talked about growing up playing with Thaniel in the woods. Thaniel is the spiritual embodiment of the land. He sees a way to fix what has been destroyed with our help and he can trust us because we all benefit from figuring out whats going on.
Edit: Its also because he is a good person and wants to help people. Hes a druid, hes a healer, thats what he does. I genuinely felt his concern and sympathy when he sensed our tadpole and said "Oak Father preserve you child"