No need to consume magic energy or similar resources, and there is no wear and tear. It only requires undead death qi to repair and recharge. It's indeed a very cost-effective item.
Moreover, there happens to be a large Burial Ground filled with undead qi in the area where Zong Shen resides.
For the Nightmare Doll, this is an inexhaustible treasure ground.
It also broadened Zong Shen's perspective. As a neutral force suddenly descending as a Lord's influence, theoretically, any troop type can be recruited. It is the most unconstrained and free new power in this world.
Without factors of faction, historical factors, or many constraints, theoretically, a Lord can accept and accommodate any soldiers, develop in any direction, and even become an invincible Lord who accommodates both good and evil, suppressing everything to unify the entire continent.
