I went kinda crazy on this one. I started with a coat of Bad Moon Yellow, then a heavy drybrush of Blazing Orange, then a lighter drybrush of Blood Red, and an even lighter drybrush (but still enough to give almost complete coverage) of Chaos Black mixed with Codex Gray. The result was a mostly-black mini with red, orange, and yellow showing in layers in the cracks between the rocky parts of the mini, like its inner parts were molten rock but the outer parts had cooled to normal stone. I then made a mottled area of gray and dark gray on my pallette and sponged it all over the mini to give an irregular coloration to the whole figure. I painted the headstone, ivy, and skull on the base, and then flocked in in brown near the elemental's body and green elsewhere, then drybrushed a light amount of red and yellow on the brown parts so that it looked like it was erupting from a grassy area and burning the grass where it stood.
I'm using this mini to represent the thermic elemental template.