I don't really know Zone-tan, but I love the Eldritch abomination design here! The execution here is pretty decent, I'd just recommend experimenting with different methods of shading and a little practice with drawing different shapes such as the tentacles, skulls, and arm. You really are doing pretty well with what you've got, and you've got the right ideas for where to put shading, I just feel that a little more finesse with the airbrush tool, or figuring out another method, would allow you to take it to the next level.

Either way, I love the art, I'm curious to see where you go from here!