Marvel HeroClix: X-Men House of X Booster Brick - Rules of Play says:

This 5-figure booster release features many fan-favorite themes that Clix and comics fans alike will love including the Quiet Council, the Five, Excalibur, X-Force, Marauders, Horsemen of Apocalypse, Otherworld, Starjammers, and more! Plenty of beloved characters that have never-been-Clixed will appear, as will characters that have been absent from HeroClix, and even some characters who we've never seen like this before! Apocalypse, Moira, Glob Herman, Maggott, Rasputin, Old Man Phoenix, and many more are coming to rock the tabletop!