The Episode 2: Atlas Mugged Add-on for Tales from the Borderlands has 7 achievements worth 200 gamerscore.
Completed Chapter 1 of Episode 2
Completed Chapter 2 of Episode 2
Completed Chapter 3 of Episode 2
Completed Chapter 4 of Episode 2
Completed Chapter 5 of Episode 2
Completed Chapter 6 of Episode 2
Completed Episode 2