Explanation (Feel free to skip): On my server, I use a plugin called MythicMobs which allows me to create awesome mobs, and custom drops for them. The issue is with the custom items I've created. During the update to 1.9 from 1.8 (both spigot and the plugin I mention), some of these custom items, wether in player's inventories, enderchests, normal chests & other cointainers... have suffered some formating issues and now have inadequate properties such as 0 cooldown delay. Also, in many other situations, a server admin may sometimes find himself in the situation of a corrupt economy & or broken game balance, due to certain presence of specific undesired items. What I need help with: I need some advice on how to remove specific existing items completely from the server's stored data (Not block or remove the item's availability), and in an efficient way. I know it's not a simple task, because these item's data's are somewhere inside the minecraft data files. The thing is, I don't understand very well how these files are structured, as I haven't explored them too much in the past, this is why I ask for help in efficiently finding the items I want to target, and remove them from the world's presence. I thank in advance!