Build an enormous dark fortress int...

Build an enormous dark fortress integrated into a volcanic mountain and crater. The fortress should appear carved out of and built through the mountain rather than sitting on top of it. Create enormous gates emerging from cliffs, fortress terraces following the terrain, towers embedded at different elevations, internal courtyards, bridges across volcanic fissures, and a huge central throne-fortress overlooking the crater. Use blackstone, deepslate, basalt, dark blocks, and restrained red/lava accents. Avoid excessive exposed lava and generic Nether styling. The architecture should be the spectacle.