The dark green bubbles on the base are liquid green stuff. This is the first time I've used it, and it was goopier than I expected. I ended up thinning a little with water before using it, much like I do with milliput. Once thinned it took a pretty nice hemisphere shape. I should have held it upside down a little while to let it set better.
The base is cork layers, Vallejo black lava for texture and little metal bits (grating and a gear) from the GW 40k basing set. I ended up carving down some spots for his feet to avoid the ever popular "floating on the base" look. I hate that, but it's really hard to avoid if you are making bases with any kind of complexity.
Oh, and tonight's secret sauce? Vallejo Model Color "black glaze" (70855.) I used it like crazy tonight, sometimes straight and sometimes mixed with a little brown glaze (70854.) I know shading with black has problems, but it just worked for me tonight. It certainly has a a different quality of color than VMC black (70950) does.