when you get enough stones to give you 100 fury, you put it on whichever partner you want to skill in the first round. keep in mind a basic stone gives 8 fury, but only 4 in battle. so you need enough stones to get 100 fury, 50 in battle.
thanks for the reply!
so how many stone should i need to cast 100 fury?
i assume for 1lvl4 8% fury stone will give 1lvl2 fury stone 10% when you synthesize em