He's talking about legacy coins that you buy for 500 annihilation xp each, which are currently useless. You do receive the coin, but there's no way to find out that you can redeem it in /legacy if you have like 5000 of them for a temporary legacy rank, which was there while legacy ranks were unavailable in the store. That's too much xp for a legacy rank and I'm 99% sure no one has tried to get a rank that way. IMO it should be removed from the anni store. Sorry, @Xhandre, but you most likely won't be getting your 500 xp back.
Legacy Tokens can give you ranks for 2 weeks. Though, you have to get a certain amount of them to achieve the rank by voting. I think it is currently bugged atm.