Everyone's used what I would put here.
Seriously epic. There is only one thing I would actually change about this if I had any part in it, and that's the flashback to 5.1. Just to make things a bit clearer.
Other than that, beautifully made and worth the wait. I (along with many others more than likely) am glad that the effect on Dust was not permanent, and relish the fact that there is a chance for his berserk side to show up once again. I also enjoy how you've progressed with an actual story, as opposed to the previous Bunnykills that were just one offs.
I also like the aspect you have with Smoke. He's been in two other installments, once as a villain, then as an ally, and now as a villain again. Though the previous ones, as stated before, have nothing to do with each other, they still put together a personality for Smoke, singling him out as a mercenary: neither good nor evil, just capitalist.
I also like the reworking of Dr. Sludge. He was introduced with Dust as his project, but was killed before he could see what his creation could do. This time Sludge got first hand experience, and that just makes his death all the sweeter.
All that's left to say is you've made sure to keep your fan base sitting on the edge of their seats, waiting for the next scrap of delicious meat that is Bunnykill to be tossed into the pen. And I feel confident in saying that this is not the last we've seen of Snowball, though whether or not he will reappear in this storyline (if, that is, you continue it) is questionable.
Thank you for the wonderful flash!
5/5
10/10
~Argent