here's what I would do for Tomb Kings in Sigmar
>Renamed as Obsidian Kings
>Death Grand Alliance but cannot take Nagash because Nagash is a BITCH ASS MOTHAFUCKA
>Elite heavy army, "every man a king" sorta mindset
>Bones are coated in obsidian/other sorta glassy material, keeps them from being controlled by Nagash and acts as armor
>Animated statues have obsidian chunks strewn about to give them power
>They use undead slaves for menial work and on the rare occasion as meat shields