Really well done. Very alien looking. Really great use of those crystal beast "eggs" pieces, and the trans-blue spikes. I also really like the design of the legs and the back of the MOC. Everything is covered up nicely. Good stuff.
I love the aesthetic of this moc, being a bulky hunch-back with bony appendages as if to indicate that he lost his arms while in prison. He really does look like he's been in exile (prison, what have you) for a very long time. If you were to rebuild him, I suggest one arm being bulky and fully developed while keeping the bony appendages on the other side. Also give him shackles.