Cinder Flask of the Zealot

This clay flask, shaped like a skull and stoppered with wax, contains a viscous fluid that simmers with the heat of a dying ember. When consumed, it grants the drinker resistance to fire damage for 1 hour. However, the drinker must succeed on a DC 12 Constitution saving throw or be overcome by a burning desire to spread chaos and destruction, imposing disadvantage on all Wisdom saving throws for the duration of the effect. This liquid is made from the remnants of burned offerings and the residual ash collected by Ash Zealots during their rituals. While it provides temporary power against flames, it taints the drinker's aspirations with the chaotic fervor of the Ash Zealots, mirroring their twisted ambitions.