For This One, You Have To Beat A Deep Dive At "Challenge Rank 20".
- This Does Not Mean Beat A Level 20 Deep Dive, This Means You Must Beat Deep Dives Until Your Group Level Is 20, Then Beat Another One.
I Won A Level 20 Deep Dive, But It Didn't Give Me The Achievement, So You Must Beat 19 Deep Dives Before This One For This Achievement To Pop.
- Current Group Challenge Level Is Displayed On The "Season" Tab In Your Journal.
Good Luck!