The first concept art reveals Doctor Doom sitting on his throne (possibly in Latveria) with Doctor Strange ... set to take place in Avengers Doomsday. If you look at the background of the scene ...

but the first appearance of the Astral Plane came years before the Shadow King ever existed. The Astral Plane was an important part of the early Doctor Strange stories, by Stan Lee and Steve Ditko ...

Purported Doctor Strange 2 concept art showing various Avengers. Image source: Instagram In the first row, we have Doctor Strange (Benedict Cumberbatch), Wong (Benedict Wong), America Chavez ...