How do I do "Storming the City" through Zigur?

[Thelo]

My character sides with Zigur / Anti-magic, and my "Storming the City" quest log currently ends with:

* You have learned the real threat comes from a rogue Archmage, a Tempest. You have been shown a secret entrance to his stronghold.

Where should I actually go to access this stronghold? Talking to Protector Myssil just gives me the default dialog "I am Protector Myssil. Welcome to Zigur." with the sole option "a) Farewell, Protector.".

[starsapphire]

It's in north east mountains of the map, near daikara.

[Thelo]

Got it, thanks.