Tony DeZuniga does the art on both the Phantom Stranger and Dr. Thirteen stories in Phantom Stranger 18 (March/April 1972), although Neal Adams remains on the cover.
While last issue the Phantom Stranger played a very supper-hero type role in his story, this time around Len Wein keeps the character more on the sidelines, like an observer, although he does open the tale by coming to the rescue of a young woman who falls from her sailboat into the ocean at the top of the tale.
The story centres on the girl, her father, and a mysterious sailor who takes an interest in her. It's all very Gothic romance-y, and De Zuniga does a great job playing this up with his art.
The sailor tells the woman a story, the legend of the Flying Dutchman, which is probably more familiar nowadays as the plot from the Tales of the Black Freighter comic from Watchman, of a sailor lost at sea who returns home consumed with jealousy, and murders his wife for no reason. He is cursed to sail forever until he finds a woman who could love him.
This doesn't bother the girl at all, although her father is none too keen on having a cursed ghost as a son-in-law. The Phantom Stranger tries to stop the girl from going with him, but she insists that she has found true love, and a purpose, and he allows her to sail off into eternity with him.
Steve Skeates does the scripting on the Dr. Thirteen story, which is a fair bit different from his other stories. Dr. Thirteen and his wife Marie attend a seance, and see a strange figure materialize in the room. Sometimes the figure is intangible, and at other times Dr. Thirteen is able to make physical contact with it. Every time it appears, those in the room wind up short of breath.
Dr. Thirteen notices other odd effects, static electricity discharges, and the walls of the room buckling, as he tries his best to attack the entity.
In this case, Dr. Thirteen is not dealing with a hoax, but also not with anything supernatural. It's an alien invasion! They have come to Earth to steal the air. Dr. Thirteen finally succeeds in knocking them down, and then lies to the creatures, threatening them with non-existent advanced weaponry. The story concludes as he argues with those running the seance, who insist that it was their rituals that drew the aliens, while Thirteen is sure it was just coincidence.