Shadows: Awakening

There is a finite amount of experience in this game since enemies do not respawn, but I don't think it's possible to miss this achievement. The enemies in chapter 6 give incredible amounts of experience, as long as you are level 26 or 27 you should get to 30 by the end of chapter 6. Note that in Fallen Eagle Pass you can go south from the cenotaph to find more enemies that aren't on the main path, and in Upper Kyallisar you can go east instead of west to the villa to find enemies that aren't on the main path.