I finally managed to get the House of El Warsuit Back Style to drop from a Promethium Lockbox while I was playing on my alt ice villain. As luck would have it, I also had the House of El Warsuit Chest Style as an alternative to choose from the same Promethium Lockbox. There was no hesitation on my part. I immediately chose the back style as I had been desiring it the moment I found out we villains could get hero styles via Promethium Lockbox drops. In Feb this year I got the Sunstone Bulwark chest style, so that's about 8 months between getting that and getting the House of El Warsuit back today. YES!