How to donate underworld keys

How can I donate Underworld Keys?

Underworld Keys can be donated in the Underworld Gates alliance building. If your alliance has already build this building it is available via the Alliance - Territory - Other menu. When you click on the coordinates beneath the Underworld Gates you will go to the building on the map. If you see a Donate button when opening the building, you can Donate. If you see three Villains, the donations are full and your alliance leaders (r4 and r5) can open the Underworld Gates to battle the Underworld Villain, when the cooldown timer is also finished.