Vault of the Onyx Citadel

With an army of their own, the heroes finally wage war against the Ironfang Legion in the climactic conclusion of the Ironfang Invasion Adventure Path! To end the hobgoblin threat once and for all, they must assault the Onyx Citadel—an ancient fortress on the Plane of Earth constructed eons ago by the mysterious Vault Builders—explore its alien landscape, and undermine the inhuman forces. Can the heroes fight their way past the Ironfang Legion's greatest leaders and confront General Azaersi before she activates her ultimate weapon: A doomsday device that will wipe out not only Nirmathas, but the surrounding nations as well?

For 16th level characters.