Pathfinder RPG: Vault of the Onyx Citadel (Ironfang Invasion 6 of 6) Adventure Path #120

For months, the merciless Ironfang Legion has struck out against humanity from its impenetrable, otherworldly Onyx Citadel! But now in possession of a key to this stronghold, the bold adventurers must rally their allies, breach the barrier between worlds, tame an alien wilderness, and finally bring the fight to their hobgoblin conquerors! Can the heroes best the Legion's most devious commanders, including the unparalleled warrior-general Azaersi, or will they fall as readily as their homeland before hobgoblin blades?