http://imgur.com/w41764x This "empire drop" has been around for a long time most likely intended for a new boss such as the mysterious statue however I would like to see it officially introduced into the game. My solution is to make it a tech lab item that gives 0.01% damage mitigation (stacks 500 times), this will help revive gifting in the game and also make adding allies easier since there aren't as many people posting their codes in world chat as there used to be.
Pretty sure Empire Drop just means they haven't released the content yet, and you've reached the max level for that upgrade. I could be wrong, but that's the impression I've had from it.
Not an actual item, just unreleased upgrades/content