With AoS 2.0 I really enjoy how the realms are coming to life, with more description and even bonus rules. Because of this with each army I start work on I try to pick a realm and base them accordingly. I put most of the realm representation in the basing of the army.
I have a bigger picture idea working up to ArchAeon and the Everchosen where I want each of the non-daemon chaos allegiance factions based on being from a distinct realm, from each other, and the daemon side to be the same realm as the mortal halves but with a realm of chaos twist. So for example Nurgle Rotbringers May have realm of life bases and the Nurgle Daemons would have the same realm of life base, but with corruption and decay added. Then Archaeons basing would be a circle of transition between the 8 basing designs,4 realms both with and without chaos taint.
I already have allocated Aqushy, realm of fire, to Tzeench Arcanists which ruled out that as an option. I wanted a darkish basing so that the lighter bone elements of the armour contrasted. I eventually chose Chamon, the realm of metal, as I thought this would be a great setting for an army who through known for being crazed have a large dependence on the forging of weapons and armour. It will also, over time, be a good realm to be able to build up a faction narrative beyond drinking blood out of gathered skulls.
For the basing I used cork with texture/grit paint to represent the earth which I dry brushed with metallics and finally applied a gloss black wash to darken it down. Then I mixed metallic paint, in this case Vallejo gold, with gloss varnish to created a flow of molten metal within the cracked earth. I allowed the metal to dry and then reapplied 1-2 more times to create volume.