Self-explanatory archers, they function as anti-range, denying other ranged units. You don't want them targeting the main pushes unless you have no other immediate targets to pursue, like other ranged and light-armored targets. Be wary of getting dived as people do not like this unit. The reason for going bottom line is because it pretty much provides more damage than top line OVERALL, so when you get done taking out ranged (which are relatively killed in 1-2 shots from this unit), you will be better suited to go against the tasty blob targets that you want to shoot at. Last doctrine is a filler, whether you want more ammo, LDS, more damage, etc.