The on-hit: cast spell item property causes a spell to be fired on-hit, either when the wielder scores a hit (for weapons) or when the wearer is hit (for armor). The possessor of the item is considered the caster, and the other creature is the target of the spell. The caster level is listed as the "level" of the property. The usual spells can be associated with this property, as can a few "spells" specifically designed solely for use as an on-hit property (e.g. chaos shield). The latter are technically spells (as are many special abilities in the game), but they are better understood as item properties.