Ah! It ate my post! A quick overview of what I had said would be:

I can't tell what scale you're going for. The size of the countless skulls make me think it's smaller than you want, and the ripples on the blood make me think it's even smaller.

Also with the blood, the ripples would be spreading outward from where it's falling, and they'd be closer together with less height between the crests and the troughs. The pool of blood unfortunately looks more like a pool of curdling pudding.

The shadows don't match up. The walls drop shadows straight down, but have a hard light source above and to the north. The pit doesn't have any shadows at all. I'd lose the direct light, lose the shine, and stick to a soft, dim, ambient light while adding shadows to the pit.

I like each of the different stone textures, but together they don't make sense. The ground is one material, the walls are another, and the pit is a third. Maybe if they were all at least the same color pallete with the walls drifting off to black?

I think that was everything.