#Hostility: Hostility is a simple damaging effect triggered per round if the Harmony between the item and wielder is Incompatible or Opposed while being wielded/operated; Additional triggering events and effects may be in place on individual items if the Attunement Guidelines are not met. Items of faith [dedicated to a Principle] are generally the only items that, by default, have inherent #Hostility.
It is denoted in the item description as #Hostility (X) where X is the damage done each round to the wielder.