These dioramas are fairly new works, and each one is an attempt to capture a particular moment in time, in a way that a model on its own simply cannot. The first diorama captures a turning point in an old campaign, where the Imperial side broke through Chaos lines and proceeded to enact Exterminatus on a planet. In the diorama, a Victory-Class Battleship and a Lunar-Class cruiser force their way past a Chaos Hecate-Class Heavy Cruiser, turning it into a flaming hulk along the way (it didn't explode until after the Imperial vessels had safely moved out of reach!)
The second diorama is pretty self-explanatory - it is the Planet Killer doing what it does best!
(And yes, that is an LED built into the explosion).
There will be plenty more to come; custom-built Grand Cruisers, Imperial Navy and Chaos fleets, including one Chaos fleet that virtually maxes out the Capital Ship slots.
Next up, however, will be an entire Necron Harvest Fleet. Until then, thanks for viewing.