Levitz, Ditko and Wood share the final issue of Stalker, number 4 (Dec/Jan 75/76).
Staler spends this issue in Drgth's otherworldly realm. He meets a magical imp type character who challenges and guides him. Stalker battles living skeletons and dragons until he notices that none are really having any effect on him, and figures out that they are illusions.
Indeed they are. The different challenges that Stalker faces in this realm have all been planned by Drgth, who is monitoring him. Stalker is not the first to have made it to Drgth's realm, but all before him had fallen to one of his challenges, tests of courage and power.
Stalker then is sent into a region of nothingness, but his anger and desire for vengeance against Drgth prevent him from being broken and losing his sense of self. Drgth then pits him against a horde of dead warriors, presumably the ones who had fallen to Drgth and his tests in the past, but Stalker defeats those as well.
As the story ends Stalker faces Drgth and demands his soul back. Drgth explains that he has already consumed it, there is no possibility of returning it. As long as Drgth lives, Stalker's soul will be a part of him. He asks Stalker to join him, but Stalker refuses. Drgth sends Stalker back to reality, and tells him that he will pit all of his followers against him. That when Stalker finally dies, he will serve Drgth in eternal damnation. This doesn't bother Stalker, who vows to destroy Drgth and all his followers, if that is what it will take to get his soul back.
So at least this storyline does come to some sort of conclusion as the series ends. Stalker would make a couple of cameos in years to come, but only play a significant role in the late 90s as the major villain in the Justice Society Returns miniseries.