Wein and Wolfman work together on a full length Jim Aparo story in Phantom Stranger 26 (Aug/Sept. 73), which brings together the title character and the Spawn of Frankenstein back-up series. This is also the last issue illustrated by Aparo.
Dr. Thirteen is back, raging over Marie Thirteen, who is a still in a coma, for which he blames the Spawn of Frankenstein. The Phantom Stranger does not make for a welcome guest in the hospital, but the Stranger insists that he needs Terry's help urgently.
The Spawn of Frnkenstein is in the hospital, there to steal some equipment he needs to resurrect his dead creator. But along the way he has been possessed by a demonic spirit. He not only takes the machine, despite the Phantom Stranger's efforts to stop him, but steals Marie Thirteen's comatose body as well.
The demonic spirit leaves the body of the Spawn of Frankenstein and moves into that of his creator, once it has been re-animated. A second spirit takes over the body of Marie Thirteen, and together they try to kill the Spawn of Frankenstein. Meanwhile, the Phantom Stranger and Dr. Thirteen head to the house.
While fighting against the possessed bodies, the Spawn of Frankenstein determines that physical force can drive out the spirits, without harming the host bodies. So of course the way this plays out the Spawn is beating up Marie Thirteen when Terry enters the house. He tries to stop the Spawn of Frankenstein, until "Marie" turns on him. The Phantom Stranger understands what is going on, and aids the Frankenstein creature as they drive out the spirits and destroy the house. The Phantom Stranger's medallion is shown to have reflective light properties in this story.
I'm not quite sure what happened to Rachel, who was briefly seen at the top of this story. Guess she died. No one seems to care. Marie Thirteen is left comatose again, and Terry is all alone with her at the conclusion, the Spawn of Frankenstein wandering off on his own. And though Terry vows to find the Spawn again, this ends his involvement in that series. He will return in this book, though, a year down the road. By that time, Marie is all healed up and awake. So his year off is easily explained as taking care of her and helping her recuperate.