Ley Race

When you get to the area, there's an NPC standing with two mana sabers beside her. Hop on a mana saber, and start running. You need to run through 20 beams of mana energy to finish the quest; each mana beam provides a speed boost, so as you go along you'll get faster. Just follow the paths and don't worry too much, it's super easy and you're teleported back once finished.

Firstly, this page refers to the Ley Race in Val'sharah, see also:

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• Ley Race in Azsuna
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• Ley Race in Highmountain
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• Ley Race in Stormheim
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• Ley Race in Suramar
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There are way more than 20 ley lines you could go for, after a few runs I found this path to be easy and efficient. You will see some extra ley lines off to the right, but it's quicker to ignore them.
I did notice (even when I repeated the same path) that sometimes you can see them - and sometimes you can't, but if you run through the right spots you still get the energy.
/way Val'sharah 58.2, 88.8 Ley Line 1
/way Val'sharah 58.2, 88.8 Ley Line 2
/way Val'sharah 57.7, 87.0 Ley Line 3
/way Val'sharah 57.2, 85.5 Ley Line 4
/way Val'sharah 56.8, 83.4 Ley Line 5
/way Val'sharah 56.4, 81.5 Ley Line 6
/way Val'sharah 56.7, 79.5 Ley Line 7
/way Val'sharah 57.2, 78.5 Ley Line 8
/way Val'sharah 57.7, 76.2 Ley Line 9
/way Val'sharah 56.8, 71.0 Ley Line 10
/way Val'sharah 56.2, 69.5 Ley Line 11
/way Val'sharah 56.5, 67.3 Ley Line 12
/way Val'sharah 57.3, 64.6 Ley Line 13
/way Val'sharah 56.8, 62.5 Ley Line 14
/way Val'sharah 56.1, 61.6 Ley Line 15
/way Val'sharah 55.9, 59.8 Ley Line 16
/way Val'sharah 56.0, 57.7 Ley Line 17
/way Val'sharah 55.0, 53.7 Ley Line 18
/way Val'sharah 54.7, 51.5 Ley Line 19
/way Val'sharah 53.3, 50.3 Ley Line 20

Note: This first and second waypoints are in the same spot, as you get 10 energy from the first beam instead of 5 (It looks more intense too)

for everyone who wants to run on the sabre as fast as possible and not loose stacks of speed when turning, jump and turn mid-air and you shouldn't loose any of them (works for me), only time it does not work is when running up hill obviously