This is a story related mission and cannot be missed. After returning the Jade Relic to Jaguar Javier, you will be tasked with finding the Obsidian Relic in the Templo de Obsidiana. The first room indicates that you must clear each "wing" in order to reach the relic. Simply entering the temple clears the south wing and the other three are relatively straight forward platforming and fighting as you've seen before. You will learn the ability to double jump as well as head butt during this temple.
Once all four wings are cleared, a door in the middle will open and you will face Uay Pek for the Obsidian Relic. This room has shifting walls, floor and ceiling which creates obstacles and compartments. Most of the time Uay Pek is protected in a compartment firing at you and cannot be reached. Defeating the baddies will shift the room again until Uay Pek can be attacked. She takes damage pretty easily and after three waves you should defeat her popping the achievement.