Let Sleeping Mountains Lie - Cape Caem

First Available: Chapter 9
Other Requirements: Complete The Errand Prince/Meet Dino
Location: Cape Caem
Rewards: 1000 EXP (for quest) 90,000 EXP (for boss)

You start Let Sleeping Mountains Lie sometime during Chapter 9 when talking to Iris. For the first part of this quest you'll need to speak with Cindy at Hammerhead after which she'll send you to Dave over at Longwythe Rest Area in central Leide. After you speak with Dave you'll find yourself in the Longwythe Diner along with every NPC you helped throughout the game (up to a total of 14).

Technically you only have to speak with Dino to advance the story, however everyone that you speak to here will give you an item so I recommend talking to everyone. When you're done talk to Dave to leave the Diner, then you're free to head over and speak with Monica (marked on your map).

After speaking with Monica the Adamantoise will awaken and you'll have to flee. Now isn't the time we fight him, you'll want to actually listen to the game and run. Once you've avoided him the quest will complete and you'll get a pop up telling you to speak with Takka in Hammerhead to accept the appropriate Hunt for the Adamantoise. Lonely Rumblings in Longwythe is the hunt you'll need.

Before starting the fight with the Adamantoise I strongly recommend you Camp nearby and eat the best meal you have to boost your Attack Rating. The fight with the Adamantoise is going to be an extremely long one and the food buff will likely run out during that fight so any EXP boost would be pointless. Instead, we want to try to speed up the fight as much as possible, hence the attack rating buff.

For the Adamantoise fight there are two really good strategies that I would recommend. One of them involves the Ring of the Lucii and the other involves Prompto. I'll go into detail about each strategy below, you'll find a video further down the page that demonstrates these two strategies in real time.

Ring of Lucii Strategy: For this strategy you'll need to equip the Ring of Lucii on Noctis and drain the boss of his HP using it. Every time you run out of mana you'll need to teleport to a nearby warp location, aside from that this method is rather straight forward.

Prompto Strategy: I prefer this method more since you can basically AFK while you defeat the Adamantoise. All you need to do for this is to switch to Prompto and use the SMG that he has on the Adamantoise. It has unlimited ammo and you can hold down the fire button indefinitely without having to reload. Position Prompto close to the Adamantoise, like where you see me standing in the video below for maximum damage. Then you can just keep firing and watch TV!