iBlitzcrank

Lately, I've been playing iBlitzcrank (a lot), and I'm wondering which skin group the skin is related to. I keep thinking of pulsefire, but then why wouldn't riot advertise it with ezreal and caitlyn, it doesn't fit the category I guess. Was this skin just made by itself, or did it go as a collection for multiple champions. If you have been playing this game for a few years, pls reply to my confusion. Thanks.