The The Nightmare Add-on for Shadow of the Tomb Raider has 5 achievements worth 95 gamerscore.
Obtain a Bronze, Silver, or Gold medal in Time Attack for the Howl of the Monkey Gods Challenge Tomb
Obtain a Bronze, Silver or Gold medal in Score Attack for the Howl of the Monkey Gods Challenge Tomb
Obtain White Breath skill, equip Grip of Fear White Knuckle and Scales of Q Feathered Serpent
Complete the Path of Fear Side Mission
Complete the Howl of the Monkey Gods Challenge Tomb