>>95909712
You cna buy the upgrade "Paragon of Metal" for one big robot that makes it your Robo-Primarch. You put it on Thatar Calix (the one with the long cannon) and snipe their warlord.
>Which one is melee
Trick question, even your supposedly melee units are WS4 and are better off shooting. The "main" melee units would be the Myrmidon Secutors (better off just shooting plasma) adn the various fast attack boops (Vorax, Ursarax, Arlatax) but again S4 and decent guns so don't charge melee marines