LEGO LOTR: Barad-dûr™ Microscale Diorama
Barad-dûr, also known as the Dark Fortress, Sauron's central stronghold in Mordor.
The underside has a hole through which you can light the lava in the moat. I designed it with a smartphone flash in mind, because phones are flat, so you can place the MOC on top of them.
I went with the usual 8 by 8 base for the diorama, but this time the outline is dark gray instead of black, and some elements overlap it, so technically it's more like a 10 by 10.
The piece I used for the eye has a decorated variant with the actual Black Eye of Sauron printed on it, but it is super rare.