From the universe of the game "Mutants and Masterminds RPG," this card game utilizes the same system used for "Sentinels of the Multiverse" ("SoTM" hereafter). Christopher Badell, the game designer of one SoTM, is listed as having done the "Game Design, Rules Writing" (which means this is Christopher's SoTM game system).This set is not an expansion and comes with all one would need to play the game.

The game is collaborative, and part of what you want to do is have your heroes work together to win. With this product, you get 10 hero decks (with 2 different hero cards -- 2 for each hero deck-- to play with), 4 oversized Villain Cards (and 4 Villain decks), and 4 environment decks. Each Hero/Villain has a complexity on it (between 1-3) to make it easier to play at first and then to ramp up for more combo fun (1s are easier, and 3s are more complex).

All in all, this is well worth the money!