Maintenance for the week of October 6:
• PC/Mac: No maintenance – October 6
• ESO Store and Account System for maintenance – October 7, 6:00AM EDT (10:00 UTC) - 4:00PM EDT (20:00 UTC)
It is called the "Chaosball Cohort" and was rewarded for watching the Update 44 preview livestream. See article below. Not sure if it will be back but often these rewards do get recycled.