Just as there's the official FB group, I believe that there should also be an official Discord server. To those who don't know what discord is, it's an application similar to skype, but is more oriented towards gamers and can handle more people.
Discord is useful in the fact that there can be multiple lobbies: maybe one to ask for dungeon defenses and helpers can send images of defense layout or linking youtube vids, maybe a lobby to share raids of a 999,999,999 gem, or a lobby to request help for certain things.
Discord is nice in the sense that you can chat with other users easily, can send images through the phone's camera roll, and can be installed on the phone or the computer. Some people may not want to use FB and discord can be a great alternative of a community-based group.