Final Fantasy XV is littered with dungeons which can be icy caverns, hot volcanoes, or dark catacombs. Some of them can really be challenging but no matter how difficult they may be, there is always a reward waiting at the end of the game.
Fociaugh Hollow is part of the Trial of Ramuah quest in Chapter 5: Dark Clouds. This dungeon is where you can find the third runestone in order to obtain the blessing of Ramuh. The recommended level for this quest is Level 22 and 1,000 XP.
Fociaugh Hollow is found above the Malacchi Hills bact at the East Wiz Chocobo Post. Before you leave the place, a group of imperials will try to lay waste at you at the entrance of the dungeon but you can easily defeat them.
Once you get the runestone, Noctis will receive the blessing of the gods together with a vision. This blessing will prove helpful as you journey, especially when Noctis finds himself in grave danger.
You'll find the Daurell Caverns in Shier Heights which is fairly easy to access. However, the numerous enemies you'll find along the way will prove a very big challenge. The required level in order to access this dungeon smoothly is Level 28 with 4,000 XP.
The enemies in this dungeon are especially weak to polearms. Your swords and greatswords are also useful. The biggest challenge, however, will be the Necromancers, which are one of your strongest enemies. Be careful of their mist attack and use either a polearm or greatsword to take them down immediately.
You'll find two paths as you progress inside the dungeon. The shorter one is at the short-east which will also lead you to the Ascension coin. The longer path is on the north and will take you onward.