Batman Legends of the Dark Knight 37 (1989)

“Mercy” was a by-the-book Gotham City cop…until her partner was savagely murdered by the Cossack, a brutal champion of the illegal street-fighting circuit. She turned to Batman for help, and he trained her to fight. Now, out to avenge her late partner, she has to enter the ‘Blood Pit’ and Batman has to stop her. Written by Dan Abnett and Andy Lanning, with art and cover by Colin MacNeil.