Daemons. They all have invulnerable saves, Deep Strike onto the table, have hard-hitting close combat troops, some funky abilities and big walkers backing them up.
I didn't want to break out Ad-Mech so early, but that's what's coming to mind.
Invulnerable saves - Refractor fields, check!
Deep Strike - I can easily see an Ad-Mech force being teleported onto the battlefield, either from an orbiting ship or underground facility. Check!
Close combat - servitors and cyborg soldiers with all kinds of stabby additions. Check!
Funky abilities - "Any sufficiently advanced technology..." and all that. Check!
Big walkers - Big weapon platforms, funky tanks, knights - Check!
This is one of the books I don't have, so I'm sure I'm missing some tricks. But the basic force that came to mind is a bunch of combat-cyborgs (Bloodletters) backed up by heavy combat servitors (Bloodcrushers), cyborg attack beasts (Flesh Hounds) and Knights/funky walkers (Soul Grinders). Add in some Prime Units (Heralds) and you're good to go with a pretty mono-"Khorne" force.
You could add other things of course like some Flamers as gun servitors, vat-grown abominations as Greater Daemons, attack cherubs as furies, etc. if desired.
What other Ad-Mech "daemons" might you like to see on the table or create yourself?