it is not from just filling the bags, you have to progress the quest line to the quest where you have to wear saladin's mask that you get for free from Tyra in the temple and get solar ability kills and 25 axe kills all as saladin one solar 50/50 kills and one axe 25/25 kills with the mask equipped. essentially just run around hoarded areas in the plaguelands wearing his mask with your solar subclass item. But.....you must progress in the quest line for the Festival to achieve this. I think it might be the 3rd quest from the list. Good luck.