Completed using gradient mesh and a few parts in plain vector.
A step by step tutorials on how to mesh this Diablo was submitted and can be viewed as follow :

Part 1 - Gradient Mesh - Basic : covers the mesh tool and how to add and manipulate mesh line.
* Go to [link] for Gradient Mesh Tutorial ( Part 1 )

Part 2 - Gradient Mesh - Color & Shading : Sampling and applying color.
* Go to [link] for Gradient Mesh Tutorial ( Part 2 )

Part 3 - Plain Vector - mainly by using the pen tool, pathfinder, gradent tool to complete work.
* Go to [link] for Gradient Mesh Tutorial ( Part 3 )

>> Go to [link] to view outline/wireframe of the Diablo