Batman / Teenage Mutant Ninja Turtles Adventures #2

Synopsis

After escaping Arkham, The Joker and Harley Quinn find themselves in New York City on the Turtles' world and meet up with Shredder and the Foot Clan. Batman, Robin, and Batgirl investigate another portal in Gotham City, which leads to them crossing over as well and encountering the Turtles. The heroes don't know what to make of each other and begin to battle, but they are soon forced to join forces when confronted by Snakeweed and Poison Ivy.