Warning: contains spoilers for DC vs. Vampires: Killers #1!
In the limited series DC vs. Vampires: Killers, Harley Quinn's long-evident plot armor finally gets literal with an awesome new power. As every other living DC hero and villain struggles to stay alive against an army of the undead, Harley's new ability makes her one of the resistance's strongest assets.
DC vs. Vampires has the heroes of the DC universe take on an undead menace, similar to the popular series DCeased. As a vampiric threat begins to pick off the Justice League one-by-one, Batman endeavors to get to the bottom of it, knowing anyone could be turned into a vampire already. After Dick Grayson is surprisingly revealed to be the Vampire King and takes out several members of the Bat-Family from the inside, the heroes are overrun, and the vampires reign supreme. A tie-in entitled DC vs Vampires: Killers #1 sees resistance member Jim Gordon deliver a vial of Lex Luthor's blood, one of the only things able to kill a vampire, to Harley Quinn, now the leader of an underground crime network.
Related: Suicide Squad Redefines the One Thing Everyone Knows About the Franchise
DC vs. Vampires: Killers #1, from Matthew Rosenberg, Mike Bowden and Eduardo Mello, set after the main title's sixth issue, focuses on Harley Quinn and her new role as a crime boss. When Catwoman reveals herself to be a vampire and tries to bite her ex-friend, Harley makes a potentially game-changing reveal: she has injected herself with Lex Luthor's blood. This grants her immunity to vampire infection and actually kills Catwoman when she tries to feed on Harley.
Harley's new ability is a major asset in the resistance's efforts against the vampires, as she now has proof that Lex's blood can
Read more on screenrant.com