Designing a Bioweapon

[Rev. Tiberius Jackhammer]

So, I'm slowly working on a [URL="http://wh40k.lexicanum.com/wiki/Slaugth#.T-I1UitYs4o"]Slaugth (maggot-men)[/URL] army as well as my H'rud. ([URL="http://i1187.photobucket.com/albums/z399/RevTibe/Slaugth360.png"]Prototype sculpt here.[/URL]) Slaugth use lots of "Constructs" - biomechanical creatures which serve as spies, workers, warriors and so forth. Their "Warrior Construct" looks like:

I'm brainstorming up some other construct designs, but what do you think would look good? A single-purpose organism designed to excel in one piece of battle? One of the designs I'm playing with is sort've a fish with a gun for a head, a grav-wheel for a tail and two spindly legs emerging from where its side-fins should be :P

Thinking more about a "what would its body be like, what would its battlefield purpose be" kinda approach than modelling - once a creature has a strong description and purpose, the model tends to come to it naturally!