Mohsar the Desertwalker (part 1)

I got my favorite caster, Mohsar, primed and ready to paint.  I wanted to do something cool for his base to show just how epic this Circle Orboros omnipotent really is... but i couldn't really think of anything outside the normal boring stuff... that is until this afternoon.

This afternoon I got a sample of some hi-density foam today from someone i'm looking at buying some bulk foam to make my own version of battlefoam trays.  They are getting rid of it SUPER CHEAP so despite not being good for miniature trays i thought i could make some cool terrain out of it.  Then it hit me.. cut a out a rough pillar and base Mohsar on a pillar of rocksalt..  I thought it sounded pretty epic considering Mohsar's bread and butter spell is Pillar of Salt..

So a rough cut test run of Mohsar on his pillar of salt:

And here are some examples of how i would try to paint it:

Anyone have any suggestions on how to pull off painting anything like the above?  I'm sure ideally there's probably a better material than hi-dens foam for this... like salt rock... lol.. but i don't really wanna hafta go buy anything else and i wanna use this foam for something lol.