"Eidoliths. They're basically greater spirits that will lend you their power if you prove yourself worthy to them. There are a lot of them too, like Brynhildr, Shiva and Nix, Odin, Alexander, and a lot more. But there's a catch, the Eidoliths will only respond to certain people, and that person must fight the Eidolith alone." Makoto explained.