Holding Back The Dark - Lestallum
First Available: Chapter 8
Other Requirements: Complete Power to the Pylons
Rewards: 2,000 EXP & 2,500 Gil
After you complete all of the Power to the Pylons quests and return to Holly you'll be able to accept Holding Back the Dark.
For this quest the first thing you'll need to do is travel to Burbost Souvenir Emporium which is located west from Lestallum along the road. You can Fast Travel here to greatly decrease the amount of time it takes to get here. After you inspect the machine in the back of the facility your quest will update with a new location, Coernix Station - Cauthess.
This time the machine that we have to inspect is just a tad bit north of the Coernix Station, walk on over to it and it's a rinse/repeat of last time. Note: There is a Debased Coin and Giant Feather on the ground nearby if you never took the time to grab it before now.
Next stop is the Cauthess Rest Area south of the Disc of Cauthess. When you arrive at this area, if this is your first time here in awhile you may also receive the quest Adventurer From Another World which takes place in the same area as this one.
After you inspect the final objective for this quest (shown above) a pack of Voretooths will attack your party, defeat them and your quest will complete - all that's left is to return to Holly to turn it in.