Demesne Spearmen are for holding the line against ranged, protecting your teammate's valuable units, and acting as the sole protector for a push (if you happen to be). Their formations from far away will provide good cover at first, but once the enemy starts engaging you, it's best to start contributing damage for your team with their Pure Attack ability (1). This will be the bane of their existance as you always want to keep this up, they do a lot of damage for a T2 unit in this state and will actually help you go toe-to-toe with higher tier units, this means they can also be used to dive but only if the situation is clear for it, they can withstand a lot, but don't be surprised when they're not up to the defense standards of Spear Sgts. Their doctrines are provided, since they have low block, and spreading them out and using their Pure Attack is the best practice, First Aid will help some of your models have a "2nd life" and continue fighting with that reduced incoming damage once their block breaks, they also tend to get flanked because of how many models they have including being a T2 unit, so Awareness doctrine is also put on by me. Of course you can try to put more block on them, but considering their block is already low; once that's gone, what will they have to fall back on? (Noble Blood 1 is supposed to be in the final slot, but for some reason the website isn't providing it at this time).