How to Defeat Kat Boss
Kat, Doc, Azurene and Ravebow worked really well for me. Only weapons are katanas and static field. Overclock the katanas and don’t overclock any other weapon: it’s Kat’s challenge for a reason.
Once you get the super katanas and overclock them, you can boost into bosses, shred them quickly, and get lots of gold vaults. Perhaps Luna would’ve been a better crew member than Azurene because of the shield recharge while moving.
I could’ve gone much further than wave 240, but I ended it on purpose out of boredom, since it would be pretty much the same gameplay over and over again.
Destructible bullets are not a problem overall because the katanas shred through them. Static field helps a bit by slowing them down.