Kalista

LeBlanc is a deceiver and has cheated, lied, stolen and deceived a nation and its people for centuries. If Kalista's the embodiment of vengeance than LeBlanc's kind of like an embodiment of betrayal. Not to mention the hand she played in Boram's death, whom she had "helped" at various points in the past. I wouldn't be surprised if Boram cursed LeBlanc and Swain with his dying breath to have his vengeance be done to them, be it by Kalista or anyone else.