I did it with a party of 4. The star of my party was lini who can close most of the locations, and with an animal ally can deal with the mountain. Also 3 cure spells don't hurt lol. My other party members were Ezrin (he is a exploration beast and I had shiedron medallion), valaros ( all his armors help with the damage), and harsk ( I just like how he helps others). It took like 8 tries, but with a little luck it was doable.