Batman: The Widening Gyre #1

Characters

Batman [Bruce Wayne]; Nightwing [Dick Grayson, also as Robin (flashback)]; Alfred Pennyworth (cameo); Gavin Adam (introduction, corpse); Mulligan (introduction, corpse); Etrigan the Demon [Jason Blood]; Atomic Skull (villain, flashback); Baron Blitzkrieg (villain, flashback); Monk (introduction, villain in Baron Blitzkrieg armor); Joker (villain); Killer Croc [Waylon Jones] (villain); Mad Hatter [Jervis Tetch] (villain); Poison Ivy [Pamela Isley] (villain); Riddler [Edward Nashton] (villain); Tweedledum [Dumfrey Tweed] (villain); Two-Face [Harvey Dent] (villain); Baphomet