This achievement is part of the story and cannot be missed.
In the Temple of Rain, at one point you will run up the back of a large dragon-esque beast (the Alebrije) to continue through the temple and it then has disappeared when you return to that area. At the end of the Temple, the beast returns and you will then be chased by it in an on-rails section.
Survive the chase and at the end you run into a golden axe, causing the bridge you have just run across to disappear. The Alebrije will fall into the lava.
**NOTE** It appears that players have been unable to unlock the achievement while playing in co-op. Not sure if a fix has been identified for this to date. (Thanks to NeoSm0ke & skyhopperk for the added info)