Add some kind of end game item to the the ancient cities for an incentive

Alright I do understand that the deep dark and the ancient cities aren't finished yet but I give a suggestion for the ancient cities, please add an end game item like the elytra that will give incentive to go to an ancient city. My idea was a grapling hook, an end game item that would make traveling around in the new caves easier and more fun! Again this would be an end game item that would be found in an item frame in the ancient city somewhere.