There are lots of things that define the Horus Heresy, but for me it’s the eclectic dreadnoughts that are properly iconic.
I included a Venator in my Ultramarines to help anchor it in Great Crusade era, the Sicaran chassis being just one of the many designs lost to the Imperium after the heresy.
As generic as the ‘Deimos’ class Rhino chassis is, it’s also the style I prefer to the Mars pattern.
Adding a maniple of murder bots to my Legion forces
The Caestus is basically a rocket powered, Astartes filled, void-ship breaching torpedo. What's not to love.
I very nearly forgot about the little Rhino in my Ultramarines. Unforgivable