Brotato

This is cumulative across all runs. I have no idea how to gauge a range of 700 in this game, but suffice to say that you should be playing with ranged weapons and boosting your Range stat as much as possible. For me, this was the default way to play with most characters anyway, unless they were specifically designed for a melee build. Once you have your Range pumped up above 150-200 (this was a common occurrence for me when focusing on ranged builds), you can just sit in the middle of the screen while your ranged weapons wipe out enemies spawning at the edges of the screen.

Personally, I unlocked this during my very first run in this DLC, playing as Curious with a ranged build, so it should be very easy to unlock this naturally.