These well crafted Dwarventi stairs lead down into one of the three main passages of Undertown. The underfolk have cleverly made it look like a short surface streets. Some of the branching passages look like streets as well, but it is all just a facade, soon they become more mine or hall like. The streets are “lit” (dimly by any topsider’s opinion) by mage lights and a few ancient amber Dwarventi Lights.
For all the aquaducts coming into the city, there munt be a place for the water to leave. Thus, many years ago, the Blackwater Tunnels were commissioned to carry sewage away from the city buildings.
Magic should have side effects, both expected and unexpected - fortuitous and deplorable. Expected side effects add anticipation, while unexpected ones increase the drama of the scene. The result can be comedic or dire, it dpends on which circumstances work best for your game.