Get Flower One from Zunari on Windfall Island after defeating God's Tower. Bring it to the Goron Trader on Mother and Child Island (2,F) and he will give you Flower Two. Bring Flower Two to the Goron Trader on Great Fish Isle (2,D) and he will give you Flower Three. Bring Flower Three to Zunari and you will receive the Magic Shield. This allows you to cut damage taken in half, but also takes Magic Energy.