The Forsaken Add-on for Destiny 2 has 10 achievements worth 240 gamerscore.
Earn 5,000 Triumph points.
Complete a Triumph Seal.
Collect 10 Forsaken Exotic weapons or armor.
Collect 15 Forsaken Exotic weapons or pieces of armor.
Complete the "Last Wish" Raid.
Defeat a Forsaken Nightfall Boss.
Enter the Dreaming City.
Complete the "Shattered Throne" dungeon.
Win a Gambit match.
Complete a Collections Badge.