I would really appreciate some help with how alliances work and what they're good for. Thanks
We don't have exact details on how alliances will completely work in game or here on the forums, but I believe when you join in on an alliance you'll be able to have a shared forum with that alliance here on the website. But I think we'll have to wait and see what they have in store for them in the final game.
Alliances are other clans that your clan works with, if you are in a clan go to your clans destiny group page and up near your personal stats is a tab that shows your alliances.