Teen Titans Go #4

A LITTLE FREE TIME NEVER HURT...RIGHT? When Blackfire's latest doomsday machine backfires and blows up her entire invasion fleet before the Titans can leap into action, our heroes are left with a free afternoon. Good thing there's a giant sack of (Justice League) fan mail to answer! Everything's fine until they open a special delivery from one of the League's greatest foes: an Amazo robot that'll crush the Titans with its own powers! And until the postal inspector shows up, don't open other people's mail, kids.