A potion to cheat death... almost.
Argaiv Silaic, a wise, excentrical explorer and physician, once discovered the blue mushroom's secret, and had a chance to note what he found out.
Minor Cultural Modifier: The culture believes, for the soul to leave the body, the corpse' eyes must be open. So any member of that culture takes care any dead body they find has its eyes open. Doubly true for those they kill themselves, for then the corpse will surely rise as an undead hunting him.