Myrrh is a magical dewdrop from a myrrh tree used to refresh a town's crystal so then the town is safe from miasma. although the crystal must be refreshed every year, the trees will have a new drop every two years.
The heroes from Tipa move their caravan to find myrrh to save their town. But the miasma can be removed. It will be a very long journey since you'll need your chalis to have the unknown element.