If she can search Rivellon for vulnerable minds from the Hall of Echoes without needing Damian's presence it makes her seem far too powerful.
Presumably she would only be able sense strong magic, and not have the power to do anything to a disciplined or protected mind. The dragon slayer was vulnerable from a half completed ritual, and overwhelmed with the sudden gift of being a dragon knight, and yet the limit of Ygerna's abilities was merely communication.
If you don't side with him then Ygerna says she will infiltrate the city and free Behrlihn
I didn't recall that. If she knew about his imprisonment, though, she could have let him know where to find the dragon knight and gain a powerful ally (or at least he would be powerful given time to recover).
In Ego Draconis Zandalor's plan is to resurrect Ygerna because of the odd soul forging he hoped that Damian soul might go to the Hall of Echoes?
Yes.
And then in Flames of Vengeance his plan was to resurrect Behrlihn to get the Eye of the Patriarch?
I don't think he wanted to free Behrlihn, just get the Eye of the Patriarch. It's been awhile since I played through that, though.
For FoV why didn't he just seek out Bellegar first?
Maybe Zandalor didn't think he would help? It's not like Bellegar couldn't have shown up and offered to help if he had wanted to.
Actually, I thought it was rather strange when Bellegar did offer to help. He could have saved himself, and everyone else, a lot of trouble by doing that in the first place (though that would have shortened FoV).
I guess when it comes down to it, NPCs in games may need to be powerful for plot reasons, but can not do anything to save the world before the player is able to do so.
