I don’t have the vanguard helmet visible in my armory and im rank 70. How do you pre-unlock it and what are the prerequisites to unlock it? And are there any vanguard shoulders or chest or is it just a helmet?
I don’t know personally, but I’d advise you to check Halo Nation (Google Search). Their info is pretty reliable.
You need the Commendation Forerunner Destroyer, you unlock it and it becomes visible in your armory once you have killed enough Forerunner enemies in Spartan Ops to see it.
Several of the armors are unlocked via Commendations, and wont be visible until that Commendation is completed possibly 25% or so.
Regular Vanguard is Forerunner Destroyer Master
Vanguard CNVG is Flag Victory Master
Straight Vanguard is unlocks with the Forerunner destroyer one. The skinned version is unlocked with CTF Victory Master commendation. There is a chest piece and shoulders.