When you kill monsters in Impact Prime you do not get a Destroy button on the loot screen. Instead you will get an Investigate button. Clicking this will have a small chance of success.

Eventually after succesfful investigations you will find the way to the Underworld [Not yet released]

Once in the Underworld at level 1500 the Experience bar will instead become the Energy Bar and you will have "Collect" instead of Investigate on the loot screen.

Collect will gather 1-2 energy per kill, filling your energy bar up to a maximum of 5000.

This energy will be used in several as yet un-explained ways and will be required for some quest completions.