Last Stand of the 5th Crusade
For decades, demons have ruled the Worldwound. Fearsome fiends of every stripe—their mottled skin harder than iron, teeth like serrated blades, and eyes burning with Abyssal flames—roam the ruined lands that were once known as Sarkoris, leaving their mark wherever they go. Four crusades have attempted to cleanse the land, but each seems to meet a worse fate than the last. Were it not for the line of magical wardstones along the eastern and southern borders, the demons would have long ago overrun north-central Avistan and beyond.
The Fourth Crusade hasn't really ended as much as petered out, yet some refuse to accept that. Amid crippling shortages and record lows in morale among the crusaders, the Mendevian war effort teeters on the brink of collapse. Though the demonic occupation of the Worldwound is growing, as is corruption among the crusaders, a dwindling minority of paladins and priests maintain that the Fourth Crusade is still vibrant and alive, and that the turning point in the war is only a few days away.
The Fourth Crusade is anything but vibrant, but the crusaders are more right than they know about the approaching turning point in the war. It's just that the turning point is likely destined to favor the Abyss.
One of the greatest weapons arrayed against the crusaders is their own mortal ignorance. The crusaders have long held that it is the inherent disorganization of demonic hordes, coupled with the bolstering wall of the wardstones, that keeps the world safe from the Worldwound. Unfortunately, while a leaderless mass of demons is indeed a bickering tangle of chaotic, directionless violence, the demons of the Worldwound are far from leaderless. Deskari and his demon lord allies do not want merely to wipe out their enemies physically. They want to annihilate their very natures; to destroy what gives them hope. They want their enemies to fall to their own base instincts and wallow in the countless sins that will, in the end, consign their souls to the Abyss as grist for new demonic life. Only then does Deskari plan to send out the armies of the Worldwound to crush the rest of Golarion.
The corruption that has grown among various crusading companies, knightly orders, and other organizations involved in the war is in large part an unavoidable result of human nature. But over the decades, it's been subtly nurtured and encouraged by the demons—particularly the secret order of the Templars of the Ivory Labyrinth. These cultists of the demon lord Baphomet have infiltrated every major group among the crusaders, working at undermining their morale and corrupting purity from within even as the demon host of the Worldwound relentlessly attacks them from without. For a time, the Templars were content to sow seeds of corruption and lay foundations for rebellion and disorder, but Deskari has grown impatient. A hundred years after the death of his old nemesis Aroden, Deskari has set his end game in motion, and Baphomet and his cult are hastening to comply by stepping up their acts of corruption and treachery within the ranks.