u/KeyEconomics1411

I have the rulebooks, but I still don't understand it at all. As far as I can tell there's nothing in the Mechanicum detachments that unlock Fast Attack, meaning I can't take Vulturax? I just want a simple list of Bolter Castellax as objective holders, Thallax as mobile assault troops backed up by some Vulturax and 3 Krios but I have no idea how to make this list