Complex sentence: Coinciding with the Green Arrow/Black Canary wedding special event, an issue of the miniseries The Four Horsemen has Snapper eavesdropping on Superman, Batman and Wonder Woman using a communications and tracking system indicating the involvement of the metahuman policing agency known as Checkmate.
Split into simpler sentences: Coinciding with the Green Arrow/Black Canary wedding special event, an issue of the miniseries "The Four Horsemen" has Snapper eavesdropping on Superman, Batman and Wonder Woman using a communications and tracking system. This indicates the involvement of the metahuman policing agency known as Checkmate.