Puzzle: Puzzling Portals (D&D 5e)

Yet another aged door made of old timber and rusting iron? Why? Why not a Distracting Door so festooned with possible mechanisms that opening it is daunting? Or a Prison Gate that isn't a proper door at all but an even more impervious and discerning barrier? Or a Reflecting Portal that drags the unwary into greater danger? Forget the hardware store—this is the place to pick out your next door. Daedal door designs by Marc Kenobi, illustrated by Sergio Villa.