Ben 10 The Rise of Hex

I managed to get 3 achivements in one go with this method.

go to survival mode and go to the far left, duck and continue to punch the re spawning enemy, a flying enemy appears at the 2 min mark and then 3 then 4. I used the monster that is second left from the top the big monster dinosaur looking thing. You should get 5 kills, 5 mins survival and 300 kills this way