The bases were done over a black undercoat (obviously) - which was then repeatedly highlighted in sequence as follows: Skavenblight Dinge - Stormvermin Fur - Dawnstone - Ceramite White
I used basic dry-brushing to lay those colors down as I feel thats simply the easiest and most effective way to paint bases.
On the Exarchs' bases I painted what looks to be a broken hull of some poor victim's tank/vehicle with basic metallics - but added some rust effects to really bring it out. I won't go into detail on that in this post but expect a Step-By-Step on rust effects sometime in the near future!
I also brought up the colors in the rocks that their back feet are standing on to make it pop a little more from the rest of the base. This was done by painting/blending on the previously drybrushed colors. I then washed it with Nuln Oil to bring all the colors together.