Cure for Call of Lidaha

Historically, the mountainous area of Lidaha has been impassable, blocking all passage south of Dragon's Rest toward the Principality of Making. The mountain region itself presents no more difficult terrain than any other number of passes through Dragon's Meeting, but the area is infested with a particularly dangerous form of fungus, the Lidaha Toadstool. The fungus emits spores that infest most mammals and transforms them into mindless servants of the fungus. This often just manifests in the host wandering to where the fungus grows and laying down to die, but occasionally the hosts will perform more violent attempts at gathering additional nourishment for the fungus. This infection is known as the Call of Lidaha. Luckily the fungus only grows in the cold climate of the mountain passes, and has not spread into the lands of Shifract or Gler. 
Ten years ago, a number of Atonion scholars arrived and performed a number of rituals and experiments on the border of Lidaha, before retreating back to Aton again. A year later, a cure for the Call of Lidaha was announced by the scholars. Like all their knowledge, this was freely traded, and a number of more daring merchants paid for the cure in order to travel to Making through this new route. When news of their safe passage spread, more and more bought access to the cure, and it soon lost value for the scholars of Aton as the secret spread.
In effect, the cure is simple. The right combination of roots and herbs, boiled into a tea, provides immunity to the Call of Lidaha. The immunity appears to be permanent, and people have begun taking up residency in Lidaha, enjoying the open lands available, despite their mountain surroundings. One of the things the residents have been doing, is clearing out any sign of the Lidaha Toadstool, exterminating them as best possible, but there is rumours of some residents growing and trading the toadstool, selling it as a particularly potent toxin.