While it was not the easiest to assemble, all I can say is wow this is impressive. The first of Iron Studios DC Battle Dioramas by Ivan Reis.
Unboxing vid https://www.youtube.com/watch?v=A5gYZ3zFVgc
Thanks for the info & congrats on your find!!
It's an excellent piece. Unfortunately, they don't have it online. I refuse to pay the eBay prices. Maybe after actually set up a display room.