After splitting zombies left and right, Yaiba explains to Miss Monday how his sword came to be known as Heartless.
Batman: Arkham Knight - Batgirl Begins (2015) #1
Hack/Slash Omnibus, Vol. 1
Batman Eternal Vol. 1
Dungeons & Dragons: The Legend of Drizzt, Vol. 3: Sojourn
Batman Eternal Vol. 2
Nightwing Vol. 1: Better Than Batman