Adventure Seed: Dr. Strange and the Ghostbusters

What if...

The Ghostbusters accidentally capture the astral body of Dr. Strange after mistaking it for a ghost and store it in their ecto-containment unit.  Normally the Doctor would have easily evaded their efforts but he was busy dealing with an extra-dimensional enemy and was taken unawares by their attack from the physical plane.

The wizard’s physical body is in suspended animation and is in no immediate danger but the threats the wizard normally keeps at bay are free to act in his absence.  Minions of Dormammu, Shuma-Gorath, or even Mephisto begin appearing all over the city, attacking civilians and wreaking havoc.

Once the Ghostbusters discover what they have done, the group must enter the containment unit, find the wizard’s spirit and free it.  Other ghosts trapped within the containment unit have objections to this line of actions and try to stop the "jailbreak" or escape from the unit themselves.

Adapting this adventure to Dungeons and Dragons is a bit tricky.  It is possible that the player characters have come into possession of a device that enables them to capture incorporeal, ethereal or astral beings (perhaps it is a location that they have discovered and are exploring).  They learn that the wizard who protected this device or location has vanished and, through several clues that have been left behind, learn that he is trapped inside a demiplane of sorts.  They find the portal leading into this demiplane where they must search for the missing guardian and bring him/her/it back to the Prime Material Plane before the other creatures locked within escape.

NOTE: I have spent the last few days binge-watching the cartoon and just learned that my idea has some merit to it.  In Season 1, Episode 20 (Adventures in Slime and Space), Peter references Howard the Duck running for President. This means that Howard the Duck (or the Marvel Comics character) exists in the Ghostbusters Universe.