John Constantine lives in the next episode of "Arrow" season 4. Matt Ryan reprises his role in the cancelled NBC series "Constantine" in this week's installment titled "Haunted," where he facilitates bringing the resurrected Sara Lance back to normal.

The demon hunter-slash-occult master puts his black magic to use once again in reuniting Sara's soul to her body. "If things go wrong, then we'll all be too dead to care," he tells Diggle, who raises the possibility of the process going out of true.

As stated in the synopsis for the "Arrow" season 4 episode, Constantine is Oliver's "old friend who deals with the mystical." As seen in the promo, the reluctant supernatural detective is just one call away. This is a good thing for Laurel, who has been hiding her sister in a basement, in chains.

For fans of the NBC series where Ryan first took on the role of Constantine (a show that was all too short-lived being cancelled after only one season), seeing the actor suit up as the character complete with his signature smugness once more in the trailer is just a special, glorious moment.

Constantine should do a great job at reverting Sara to the individual her family and friends know and by the time Sara bands together with heroes and villains to defeat Vandal Savage in "Legends of Tomorrow," she should be back to the way she was as they have hoped for.

Meanwhile, Ryan's stint in "Arrow" season 4 is sadly billed a one-time thing at the moment. Nonetheless, it looks like the transitory experience was as big of a treat to series lead Stephen Amell as much as it was to DC fanatics and fans of both series adaptations. "He is such a treat," Amell said via Den of Geek.

"Arrow" season 4 episode 5 "Haunted" airs Nov. 4 at 8 p.m. ET on The CW.