I Was Saved by Something Not Human...

A low level criminal is sent by his boss, Geoffrey, to execute a rival drug dealer at an abandoned warehouse to prove his loyalty. The mission goes disastrously wrong when the protagonist is ambushed, shot, and left for dead by the rival's armed crew. As he lies bleeding out, a chilling, ice-cold stranger appears and inexplicably saves his life by slaughtering the attackers. Revealing himself to be a literal embodiment of mortality ("death is my business"), the supernatural figure leaves behind a weapon and a distinct calling card, cementing a terrifying encounter with the afterlife.