In the land of Westeros, a title is a potential gateway to a life of leisure. Having land and dominion over those on it can easily lead to never having to work a single day. The Warrior's Sons, however, have eschewed all lands and titles, devoting their lives to the Seven. Instead of having servants bring them everything, they have honed their combat skills and owe their service to High Septon.
The Warrior's Sons unit box gives Lannister players a righteous arm out on the battlefield. These highly-skilled and well-equipped soldiers are an avenging scythe, cutting down those who oppose them and using their faith to bolster themselves during combat, gaining Faith tokens that they can use for different bonuses and abilities.