Sentinels of the Multiverse: Void Guard Exp. - Rules of Play says:
Sentinels of the Multiverse: Void Guard is a box set of four hero characters, complete with their own hero character cards and decks! Now, Doctor Medico, Mainstay, The Idealist, and Writhe harness the power of Oblivion Shards and fight against the end of all things. They hold back the Void when no one else can.