They're not good at anything, just face it! Mix them why? So you have a big fat target in the square so enemies won't attack your 10 gold infantry instead? Gah.
They're 11 movement, how is that good flanking? Well, at least they get to face cavalry out there that will kill them in one shot with a lance with their pathetic defense and protection, and never be able to hit at 14+ defense. Good riddance!
Oh... I mean, they're actually awesome! You should definitely sink some gold into them and use them against me.
