This section is a detailed walkthrough on how to complete Cindy’s Sidequest – Let Sleeping Mountains Lie, including the strategy to beat the Adamantoise.
After reaching Chapter 9, return to Cape Caem through the Call Umbra feature. You will then receive a phone call from Cindy that initiates the quest Let Sleeping Mountains Lie. From there, head back to Hammerhead and talk to Cindy.
After speaking to her, go to Longwythe Rest Area and talk to Dave. Then head to the diner and speak to Dino. Other sidequest vendors will be accessible if you’ve taken assignments that involve them. Each of them will give you a consumable item.
Next, talk to Monica at the east of Longwythe Peak.
The quest will be a success when you leave the area after the Adamantoise appears. You will also gain 1,000 EXP.
In order to defeat the Adamantoise, you have to accept the hunting quest Lonely Rumblings in Longwythe. Be warned that Adamantoise is the toughest beast (defense and health wise) in the entire game. A good strategy is to warp strike to either is eye or neck and use endless aerial combos (you can tilt the left analog stick in the direction of your target to immediately start a new combo once you have finished the previous one). Because of this, its important that you have obtained the Airdance nexus in the Combat Ascension tree.
If you fall from a high elevation, immediately point warp or forward warp so you won’t take unnecessary damage. A full stock of healing items is also good for this fight, as your party’s lasting power will be put to the test. Consumable buffs (such as a Magitek Booster) will also allow you to take advantage of temporarily having infinite MP to enable long aerial combos. Use the Armiger Freechain as often as you can to speed up the process of chipping away at the Adamantoise massive health.