I think it works from how many kills, revives and downs you have.
May also work with how many rounds you have done.

Okay I possibly have a theory. When you use the emp grenades on zombie's their eyes turn blue right? Well I have definitely used emp grenades on zombies and I have a 5 tallied skull with blue eyes.

But what about the next one? It looks like the booie knife right? What if you have to find the booie knife in the cabin and get a certain amount of kills with it?

haididdle wrote Okay I possibly have a theory. When you use the emp grenades on zombie's their eyes turn blue right? Well I have definitely used emp grenades on zombies and I have a 5 tallied skull with blue eyes.

But what about the next one? It looks like the booie knife right? What if you have to find the booie knife in the cabin and get a certain amount of kills with it?

Ye maybe but I've been looking around the internet and it might be on your average skill, so it balances on how many kills, revives, downs, deaths etc and gives you 1 of these emblems but im still not sure