Mana, Meta, Magic
Samiel held the Frost Crystal in his hands before he started absorbing the Frost Crystal into his Mana Core. Every being that had Mana or any other supernatural energy had the Core like people with Mana had the Mana Core or people with the Psionic Energy had the Psionic Core.
The so-called energy core was formed the moment a person Awakened and became a Professional, and it was in the Core where all of the Mana was stored. Samiel was able to sense his Mana Core within his heart somewhere, as it was glowing and absorbing the Frost Element from the Frost Crystal.
Absorption of the Frost Crystal was a relatively simple thing, as Samiel was just drawing out all the energy inside the Frost Crystal into his Mana Core, which was greedily absorbing the freezing and cold ice energy from the Frost Crystal.