Formouth Garrison is an optional Imperial base you can attack in Final Fantasy 15's late game, and is required to clear if you want to get your hands on the flying car Regalia Type F.
When you're done, be sure to check out other Final Fantasy 15 dungeons and tombs for more places to explore.
Recommended level: 46
The building is located to the east of the dirt road between Keycatrich Ruins and the Weaverwilds in Leide, and driving past it will cause Ignis to say you should take a look and add the quest to your log.
Make your way up the dirt path and climb the metal guard tower at the marker to survey the surroundings. Similar to the infiltration mission in Chapter 6 you'll have to wait for cover of darkness, but there's no stealth involved this time.
Once it starts, head forwards, bear left slightly and go through the chain link fence - there are some sleeping guards here that won't bother you, so once you're past them head in an easterly direction until you can see the generator, and prepare for a fight.
Get in a couple of blows to the generator and a squadron of assorted Imperial troops will swarm in; they're fairly low level compared to the recommendation, but what they lack in strength they make up for in numbers. Not long after the fight starts things get a little more troublesome as an MA Veles-Bis mech will enter the fray and start throwing its weight around.
There are some gun emplacements you can use to your advantage, or you can use the Warp Points to charge in for Warp Strikes, but while all this is going on don't forget that your primary goal is the generator.
After all the enemies have been subdued a second wave will spawn, and this time it will feature two mechs. We don't recommend the gun emplacements for this round - shooting at one mech will leave you vulnerable to attack from the second, and the Warp Points provide a much safer alternative.
Need more help? Our Final Fantasy 15 guide and walkthrough can provide tips on main story, as well as the open-world's many quests and activities. Learning how to get AP fast, EXP fast and money or Gil fast will aid you in many optional dungeons and tombs - including how to open and explore their locked doors. There's also plenty of interesting side-quests, too, such as the Scraps of Mystery and Professors Protege frog locations. And if you want to get around easier, you can rent a Chocobo, learn the infinite sprint trick and later in the game, get the flying car Regalia Type F. There's also more to see and do with DLC, such as Episode Gladiolus and Episode Prompto.
MA-X Dux battle
The final battle is against an MA-X Cuirass and an MA-X Dux. These are much tougher opponents than before, but on the plus side you no longer have foot soldiers to content with.
Shields and Mechanisms do most damage here, so making good use of Prompto and Gladio's Link attacks can help with the damage dealing, and it's advisable to try to focus all your damage on one of the mechs before moving on to the other - the quicker you can get down to one the better.
Assuming you've progressed far enough in the story this should now trigger the Into Unknown Frontiers quest. Make your way to Hammerhead and give Cindy the parts you've accumulated, and pretty soon you'll be the proud owner of a sweet flying car meaning you can now tackle the secret Pitioss dungeon, as well as saving yourself a few Gil as the car now no longer needs refuelling.