So far your understanding is spot on when we are talking about storing life energy through certain means. 

And I understand what your saying about real life transferring of energy isn't complex. However, the fact remains that you are goblins but don't stay that way. You need to consider the fact that your evolving and that changes you down to the cellular level. Hell reuse is practically undead at this point yet he still walks and talks like a person would you say that fire is an adequate way to help him? It's much more complex in this world because your all complex