The Callisto Protocol

This is cumulative and can be done across multiple runs.

In the wave 50 solution (Big Game Hunter), the creator and some other players mention that activating the boosts at the start of a run is preventing achievements from unlocking. This didn't happen to me but I guess it could for you.

You'll see a rampage meter at the top and the more points you get the faster it charges (I believe). Once full you can press the left and right thumbsticks ( ) in and it'll activate, giving you unlimited ammo, insta-kills etc for 30 seconds.

Rinse and repeat.

Honestly, you don't really need to worry about maximizing your points, rampage is pretty frequent. Though I've notices that environmental kills, like throwing enemies on spikes, do give a good amount of points, especially when you're at the 4x multiplier. But again, just keep playing your waves how you want and it'll charge.

This ended up being my last achievement because I rarely used it throughout my wave 50 run. If you want to get it sooner than later then every time it is ready, use it and keep up your multiplier up and get those environmental kills.