Mobile Telemancy Beacon
Source: Vendor. If you're wondering why it sometimes doesn't work — you're probably trying to use it on your alt who hasn't unlocked Oculeth's teleportation beacons yet (the introductory Oculeth questline).
The 
Mobile Telemancy Beacon is a Legion toy sold by a vendor that lets you drop a portable teleportation beacon in Suramar to return yourself and nearby players to Shal'Aran.
Guide awaiting review
Complete Oculeth's Questline
Before the toy functions, you must complete the introductory Oculeth questline on the character you intend to use it on. The toy will not work even if you have reached Nightfallen Honored without having completed that questline first.
Use the Beacon in Suramar
Activate the toy from your Toy Box to bring up a targeting reticule, then place the beacon on the ground — it is only usable in Suramar. Step into the smoke surrounding the beacon to teleport back to Shal'Aran; other players in your party can also step into your beacon to teleport alongside you. The toy has a 20-hour recharge time.
Tips
The beacon itself is unclickable after placement — you must physically walk into the smoke area to trigger the teleport.
Party members can use a beacon you dropped, so one player with the toy can serve the whole group.
