Occurs naturally in wholly non-magical, mundane locations, and under churches where faithful pray for the most simple, insignificant things.

Effect

Acts as a potent acid (1D6 irresistible damage) to creatures from beyond the threshold such as the undead, fairies, and horrors. For everything else, it feels like plain water.

Can alternatively be used as a soap to cleanse away curses and haunts for a day.