This is a clean room deep within Alexandra’s mansion, in which all of her surgeries are performed by Lumina. The custom automatic operating table is in there, as well as the spray chamber to eventually transform Alexandra into a Bane.
The spray chamber is a large cylinder at one side of the transformation room. It is used to apply the countless permanent layers for Alexandra’s Bane transformation.
Later on, this room is also used to store a couple of instances of the AlexDroid proxy.