I have design an horse archer. It has an ATK of 14. When I build a squad of ten, the ATK of the squad is 143, Which is fine as it is the ATK of an horse archer multiplied by the number of people in the squad.
But when I use that squad in battle, it is doing 1430 damage in a single shot. Thath wouldn't bother me if 143 was the ATK of a single horse archer. But it isn't the case.