IMHO, the best way to deal with powerful NPCs, especialy allies, is to put their presence in play in player's hand.
Dumbledore kind of NPCs can be viewed as a real pain for many players if they are used by the DM to bully the PCs around (Gods are even worse!).
Read/Watch again Harry Potter, and think that each time Dumbledore appears, it's because Harry's player called on Harry relationship with him, including when he do a "deus ex machina" at the Minister of Magic (book 5).
The same kind of relationship can be used with Gods in settings, like FR.
Dumbledore kind of NPCs can be viewed as a real pain for many players if they are used by the DM to bully the PCs around (Gods are even worse!).
Read/Watch again Harry Potter, and think that each time Dumbledore appears, it's because Harry's player called on Harry relationship with him, including when he do a "deus ex machina" at the Minister of Magic (book 5).
The same kind of relationship can be used with Gods in settings, like FR.