I played as a wilding and conquered Thenn, then i went to recruit thenn troops at the lords hall, and the person there says his lines, then 5 Thenn cheiftan Elite guards are added to my party at no cost, and you can spam this as much as you like, essentially giving you a free and infinite source of elite troops. Playing another game later, also as a wilding, i went to thenn without conquering it, and i could do the same thing.

(Also, how do i recruit giants, it says im not strong enough)