UPDATE: THIS METHOD NO LONGER WORKS!
METHOD 2: https://www.youtube.com/watch?v=y3HrNdT0OSU
Here is the fastest way to get 30 kills for the Vex Fanatics. Mission from Ikora called Six is the mission you want and about 1 minute in you come to the room with more than 30 of them there. Hope this helps you all!
Thanks for watching!