There are many techniques I use for basing, this is just one idea. When I started trying to take my bases to the next level that cork board my mom gave to me came in real handy. Cork is a great way fill out a base or any other scenery bit. After destroying a gift from my mom...
I started by cutting a small portion off the cork and glued it to the base. I also found the luckiest nickel that would fall into my hand out of the change jar to add some weight to the base as Astorath is somewhat top heavy.
After carving away the slot on the bottom of the base some glue was applied and the piece was set to dry.
Once dry I carved away some cork at a 45 degree angle and carved out a space for the tab on the model. Alternatively I could have pinned the model to the cork but it makes no difference in this situation.
Pretty huh? Next I carefully selected some slate I smashed to pieces with my fists and hard stares. If you're not awesome enough a hammer works too. The triangular shapes were glued in place and the piece is starting to come together.
Last I glued some sand in place. It's winter here and driveway dirt is scarce, I'd prefer driveway dirt but I doubt the sand will affect the final product.
Looks like it's ready for a model.
I like the effect this technique has on top heavy models, it creates somewhat of a cone or V shape with most models which creates a nice flow with winged models or minis with both arms raised to the sky. Like a manowar album cover.