Resistance to magical effects on FR is handled by properties. In general equipping an item that confers resistances adds a static property to the affected player. The types of resistances available are listed under "reserved". A few guidelines. Resistances up to 10% can be added without approval up to 25% is generally acceptable without penalties. Above 25%, an appropriate succeptability should be added as well. I.e. +50% fire and -50% cold.