Dungeons and Dragons has a lot going on this year, and one of the major releases is the latest book - Quests from the Infinite Staircase. It features five revamped adventures from D&D history, and runs from levels 1 through to 13. In this adventure, players meet Nafas, the primary quest giver who lives in the Censer of Dreams - his palace on the Infinite Staircase.
He was created by planar winds that blew in through the staircases infinite doors, and so he's well connected to the multiverse. This connection lets him hear the wishes of the creatures from all across it, but he can't leave the staircase - and that's where the adventurers come in. The Infinite Staircase was first mentioned in 2nd edition Planescape, and also has an honourable mention in the 2014 Dungeon Masters Guide.
It's a special way to travel through the multiverse and is physically an extra-dimensional staircase that winds up through an infinite expanse. The stairs lead to an unending number of doors that theoretically can take travellers anywhere, with the doors taking on an appearance related to the destination. Some of the doors are guarded by powerful creatures, and the first chapter of the book deals with the staircase, the doors, and rules within this expanse, answering important questions like "What happens if I fall off the staircase" and "how do I find a specific door?" There's also a huge table on sample doors that might be found, which gives an idea of how the planes the doors lead to influence th.