Kalran: Tales of the four nations/Volunteer center

Volunteers (for all intents and purposes, magitek Cyborgs), citizens of Ouroboros who chose to fight and defend their government, are uber-infantry, due to having their body enhanced by both panacea and cybernetics, which have the combined features of tanks and infantry. Volunteers are uncrushable by normal vehicles, and in fact some of the heavier ones can crush infantry. They are resistant to gun weapons but takes minor damage from cannon weapons. They can garrison structures as well and are the only units, barring the commanders epic, that can gain veterancy, though unlike the other similar factions they can only go up to three and the third is locked behind research.

But Volunteers requires mandate to purchase and they only come as a single unit, meaning its going to be harder to create large squads, and are universally fragile, or close to, meaning they must rely on the more numerous penitent infantry, vehicles, and naval craft, which can't gain veterancy, to protect them.