i know that most or all of you already know but you can fight previous fights in a "training battle", where you can get some nice weapons or armors from previous foes, and thats how i got my super cool rune blade ^ ^
this is a nice strategy, got me 4452 kills=
-its on youtube
-search "onslaught 2 railgun"
- it says get to wave 479
good strategy if you want the medium badge
some people who just start the game doesn't really see the use of the brainwash facility, until the last part where you can use "those" "things" after you killed them xP