This achievement is unlocked when you find this artifact:
#12 Pommel - 8:09
After the swamp, you eventually come across a cave with crystals. Turn your mask on as you approach the crystals and the left-most one will glow. Stand in front of the crystal, with your mask off, then turn the mask on and off. If you did it right, the next crystal will glow. Stand in front of that crystal and turn your mask on and off to make the next one glow. Repeat this process until the artifact is revealed and the achievement unlocks.