New league of evil for The Rainbooms' Adventures

Guys? Since I have The Heylin Empire/Heylins of Darkness as my and the Rainbooms' dangerous and powerful foes as the first legion of evil in my series, can some of you guys give me a new idea what should I call 2nd legion of evil as? I mean there's Charles Muntz' Empire in Jeffrey, Jaden, Hiccup & Friends' Storm Adventures, and there's The Scourge in The Eds' Adventures Series. Any suggestions?