My thoughts --
- The music is foreboding, varied, and very well orchestrated. It gives me AOE vibes, but darker, especially when other percussion instruments and synths come in. Mixing could do with a touch of polish.
- The necromancer's den sounds eerie. A little more air and it would have made my hair stand on end.
- The spellcasting FX makes me think of some sort of fire or lightning.
- The wall crumbling felt like a much taller, much hollower structure made of metal was falling down, like a ship breaking or some scaffolding or structural work twisting apart before snapping and crumbling down. I don't know if that's what you were going for, but I thought I'd put down what it evoked for me!
I feel that this befits a much darker experience overall. As I said before, this gives AOE, but darker, which is a good thing in my book. Well done, and all the very best!