God of Light: Remastered

In the tutorial you'll be introduced to the firefly. It will show you how to collect them and how to use them. In the upper right corner is where you go to use the firefly, but what the game doesn't make clear is what that number means on the firefly. That's how many seconds you have left to use it, not how many times. When you use the firefly, you move it around the screen and it shows you the path of lasers for the correct level solution to obtain all three stars. While you are using it around the screen, the time drains from it, so don't waste it. 

For this achievement, you must use the firefly on three separate occasions. You'll likely get this naturally since some levels involve a ton of mirror reflections and can be difficult to spot the solution at first. 

NOTE that the firefly only shows you the final level solution. The reason I mention this is because in later chapters there are typically various actions you need to take first before you can set the level up for its final solution, such as destroying a rock, hitting switches, etc. Bear in mind that the firefly won't help with these intermediate steps. 

The achievement will unlock mid level as soon as you use the firefly for the third time.