Spent another 50 minutes on this challenge today and this was the best attempt. Slightly farther than last time. The stun grenades kill all the flying enemies immediately in Wave 4, so that's useful. Also figured out that this mode has 3 cigarettes per challenge. They are used by taking cover and hitting LB. These cause major distractions and can be used to pull some bullshit. Tank can be tough with all the minions. I was able to use the infinite grenade glitch atleast once in another attempt but its hard to use often since you have to be running to use it. Havent gotten the timing down consistantly yet. I probably wouldnt go crazy with it if it makes certain sections too easy. Paralysing all the enemies by spamming stun grenades could be very cheap.