ItemBag system is a place that allows extensive configuration of drop from Boxes, Bosses, and Events. Following guide videos explains entire process with usage of ItemBag Editor.

ItemBag Tool location: Tools\Configuration.Editors\ItemBag.Editor
X12 Server-Side files location: IGCData\ItemBagManager

ItemBag Tool location: Tools\Configuration.Editors\ItemBag.Editor
X6 X9 Server-Side files location: IGCData\ItemBags