Worm, do you have no imagination? Just because it is called fiend doen't mean that it must be dull, boring greyscale. Besides, I do believe that FIEND refers to evil or an evil entity :
-An implacable or malicious foe; one who is diabolically wicked or cruel; an infernal being; -- applied specifically to the devil or a demon.
-Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.-
There you have it! Also, this could be a lava spawned monster, not a creature actually formed of Magma. Have you even looked at the skin?!? I look at the lava and see red, orange, yellow, all blended well. Without the stone parts, it would just look like a red blob. The stones add contrast and a sense of body structure.
By the way, good job on fixing your avatar