Batman/Superman Vol. 2: Game Over (The New 52)

The Dark Knight and the Man of Steel uncover a plot by the Toymaster to use
a secret, potentially deadly element in his new video game — the
characters created by players manifest in real life! The ultimate fighting game
results in a world-wide network of players who team up to create the most
powerful, skilled Super Heroes imaginable with one goal: To kill Batman! When
Batman and Superman are corned by the Toymaster and Mongul, they are pitted
against on another in a battle to the death, with their only hope being the The
Worlds' Finest.
Collects Batman/Superman #5-9, Batman/Superman Annual #1, and
Worlds' Finest #20-21.