Calamities explained

[MrThinker]

Judging by what he says, it is possible that Lahabrea gave him a way to come to The Source. In the first cutscene with Moenbryda in Northern Thanalan he says, "I suffered the overweening presence of Lahabrea that men might host the power of gods, only for you to undo my hard work."

It's quite possible, similar to how Elidibus gives Ardbert and co. a method to move from a Shard to the Source that the same is done for Shard based Ascians. Though, honestly, it's all a mess. I still don't know if they're ever gonna mention why Ascians no longer use Crystals of Darkness for body possession and the like.

My assumption is that when we beat Nabriales he restates that he may return everyday, for as long as it takes now that the Blessing is undone. He's also shown to immediately return from the rift in that same cutscene. To reconstitute a body without taking a physical host, even. While it is set within the Rising Stones, why would the building itself reject Ascians because we have The Blessing? By that logic, any building we've been in would be sealed to them, and that is incredibly silly.

See edited statement. Also, suffering "the overweening presence" reads to me as "I needed his help to get my plans realized even if I didnt want his help", rather than "he helped me arrive on this world". As for when he returned after his physical body was killed, that was in his spiritual form, not a physical one, which is why it could be bound to an auracite. As for why the building itself would reject Ascians; it isn't, it is a magical protection set over the building by the Blessing of Light because our character considers it 'home'. Think how Voldemort was unable to kill Harry at the Dursely's because of the magical protection residing over his 'home'.