Campaign Weekly Challeges

[Drakon21]

So i don't know about anyone else, but i do the campaign missions in 1 mission. The mission it says to do on legendary with the skulls on required for the other challange. I've found out that it is much easier with the skulls on that make the enimies always throw grenades as this lets you assainate the knights quite easy, the skull that makes enimies never run away so the knights dont run away when you try to assainate them, and the skull that ranks up the grunts, which gives them few rod cannons allowing me to pick those up and blow **** up. Anyone else use these skulls?