User blog comment:Green Ninja/Mixel Moon Madness - Wiki Plans/@comment-5344911-20150307214839

I know what are this additions. These tribes got new members coz they were most popular tribes in each series. Example:

Series 1 : Infernites

Series 2 : Frosticons

Series 3 : Glorp Corp

And each time the new series comes, they need to change the avatar of lego mixels page on Lego.com : series 1 flain, series 2 flurr and series 3 Torts.