Summary pulled directly from Steam - Some text may only be applicable to Steam platform

Learn the secret Uchu has told no one else! In order to obtain a powerful and mysterious weapon, Lara Croft must face the music in a brand-new challenge tomb, battle foes who look like but are not like any she's ever faced, and confront the deadliest enemy of all: herself. The Nightmare offers new customization options, with the Scales of Q outfit, the Grip of Fear axe, and the White Breath skill, which grants Lara's Fear Arrows the power of an area effect.

Included in the Croft Edition and Season Pass, also available separately.