To get the helmet Jun for your avatar:
Kill 100 enemies in a row without dying
To get the helmet Jorge for your avatar:
Kill four enemies in 4 seconds in matchmaking multi
For 's helmet Carter :
Finish a mission of the campaign mode in legendary without dying
To get the helmet Kat for your Avatar :
Avenge the death of a teammate in matchmaking multi
To get the helmet Emile for your avatar :
Kill an opponent who tries to kill you with a sword energy
