u/Acoldsun

I don’t know the rules but I would like to start a Death Guard Army. I have the saturnine box, Calas Typhon and a Land Raider Proteus. What else should I get and how should I build the models?

I’m also starting a Sons of horus army, for that I have the Legiones Astartes combat force, Sicaran Battle tank and Horus Ascended. Are there any model that I should interchange with one another?