To Baal0919, They probably injected him with some sort of super steroids or something like that, that had an extreme roid rage side effect. They might have also intended to put a mind control effect in, but,
snowball was about kick their asses and kill them, so they had to speed it up, causing Dust to go
crazy, killing pretty much everything in his way, including snowball. Maybe they actually intended him to kill snowball, and stay power crazy. But of course, because snowball was RIGHT THERE, they had to do it now, pushing in the incomplete serum. All in all, great animation, and great story. Goodbye Snowball, you will be remembered, you went out in victory. Dust completed your missions for you and is getting revenge for your death. Smoke is dead, Dust is fine.