Eriape cannot be rescued with her own cooperation, for she is under a mythic archmage's Dominate, and that mythic archmage will know the instant a rescue attempt becomes apparent to Eriape herself. Azkiran is not actually good enough to Dispel that Dominate, nor powerful enough to Disjoin it, and being mythic the Dominate would last through a non-mythic antimagic field or any other kind of magic that Azkiran can wield. He is a babylich, not a being like Takaral Himself.
That Dominate will not extend across planes, however, mythic or not.
...Eriape's lump of stone cannot be plane-shifted out in a lightning assault, because it is inside the palace of Cheliax beneath a Forbiddance.