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What you can also do, is a bit of an intro:

In a world, where a essential mystical energy sustains all life, a lonely waitress with a dark past, discovers, only she can defeat a superhuman nemesis, bent on destroying this source and must face him in paranormal combat.

Am I on to something?

From what you have written I still don't know what the lead character must do, so here is an attempt at a logline but without that one element (Because I really don't know what it is)
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"When an evil being set's out to control reality itself, a lonely waitress who is secretly the last of the elven race must (Do this thing) in order to stop him."

Sorry, your story is so unclear I simply can't make any useful suggestions at this point.

I think you really need to pay attention to the industry conventions we've been discussing on your post and others. Clarity is everything in a logline - I mean that - clarity in a logline will motivate a decision maker to read your script more than the concept - SERIOUSLY - I'm not just saying that.
I can't tell you how important the 'Aha!' moment is for a producer after hearing your logline. Over the years, it's gotten me more read requests than times when I told someone a logline and they didn't get that 'I get it moment' on their own.

You need an inciting incident (that means one SINGLE out of the ordinary event) that motivates the main character to take action towards achieving a clear goal.
Check out the 'Formula' tab for more details.