In order to get this achievement you must start ”Awakenings” mission chain that is available as soon you will hit 1300 on your power level. The misson giver is Ragna and the achievement will unlock while talking to Ragna for a second time, after completing this mission chains first mission.
However, reaching to a 1300 power level can be a bit of grindy and luck. By grindy I mean that you must have some serious nerves to grind some of the previous missions or tarrot card missions in a hope to get a powerful gear that will increase you’re total power level. And by luck I mean that these powerful gears do not drop from enemies so often.
For example: I was able to reach to 1300 power level after reaching character level 51 and completing a couple of DLC assigmwent missions and a lot of tarrot card missions plus the main story. In a nutshell; it is a hell of grind to get to level 1300 power level.