This is what Rhoan's energy looks like and what it looks like when it's surrounding him. (I don't have enough of the art skill to add the effect with the pic -_-)
[img]http://img1.wikia.nocookie.net/__cb20131231072300/monsterhunter/images/9/9f/MH4-Stygian_Zinogre_Render_001.png[/img]