How do you get the Mark VI helmet in Halo 4?

Games Other Halo
1

I’m rather confused on this subject. Do you has to reach a certain rank, or do you have to heat the campaign on Legendary? Thanks

2

Beat the campaign on legendary or solo legendary (forget which).

3

As stated by 343 you have to get the achievement"The Legend of 117" which is completing the campaign on legendary.