Inferno’s main forces.

I think that Inferno armies can easily do without Nightmares, Demons, and Devils; instead, you can take a Demoness, Succubus, Imp, or Parasite, along with Fire Hounds, a Balrog, and Spawn in one army, and then recruit some neutral creatures. Or, you can take a Nightmare or a Devil, but a Devil is better. I often do this; I leave the Demons in the castle and don't even build a Stable sometimes.