D&D Descent into Avernus - DM Screen - Rules of Play says:
It's time to Descend into Avernus! The ninth realm of hell, ruled by the archdevil Zariel and her untold hordes of diabolical servants. As DM it's up to you to tempt your heroes with enticing deals and visions of ultimate power and treasure as you guide them from level 1-13 as they journey from Baldur's Gate into the depths of Avernus itself. This screen has been specifically built with the DM in mind. One side boasts evocative artwork from the adventure, while the other displays helpful information for quick reference.