In the end I left the arms the way they were, the lack of balance the early stage model had disappeared as more details were added. I used tentacle makers from Green Stuff Industries to make fibre bundle muscles to complete the legs. Oddly they are relatively accurate to the shape of a person's hamstrings, tensor facia latae, glute maximus and medius, and sartorius and gricilis, admitedly with mostly the medial muscles being present. I'm a personal trainer professionally so knowing muscles is a quirk of my job, it's actually annoying when I sculpt muscles in that I can't be done with them until they are anatomically correct. But I digress.
The tail is a tentacle from a Maulerfiend, it's a really neat bit and is perfect for a tail.
The head was made by merging a Juggernaut head and a skull from the Minotaur kit. The original Juggernaut head was too flat and bulky when I added the armor plate on top, so I swapped it for the skull. I hadn't planned to cover the original eyes but it worked out that way as the blending progressed.
The horns are from a bunch of sources. You may have noticed that it may shoot off its own horns with the Rotary Cannons, I assume that it would duck it's head to fire them.
The Lightning Gun was refined quite a bit. The wooden bits on the side are from a hobby shop, I think they are meant for making dollhouse furniture. Otherwise I just added a lot of extra detail to make it look more like a high tech energy weapon then it originally did.
Otherwise I just blended the components together to unify the piece and it was done. I couldn't be happier with how it came out, to such an extent that I just bought another box of Juggernauts to build up a real hunting pack of the things. In the end I'd love to have about 6-10 of them.