there are 7 butterflies. you have to catch the blue ones. the red ones call fiends. it's not easy, but you'll get it after a while. the chest is right in front of the traveler's lodge in the thunder plains. yes, if you open it once, you can open it again. it will give you a prize for all the times you open it. for example, if you dodge it 10 times, it will give you the prize for dodging it 5 times, then the prize for dodging it 10 times. it appears when you dodge the bolts all the times in a row.