Final Fantasy 15 Dungeon Guide – Costlemark Tower

Final Fantasy 15 Dungeon Guide - Castlemark Tower
Final Fantasy XV is filled with awesome dungeons that will push Noctis and friends to their very limits. This Final Fantasy 15 Dungeon Guide – Costlemark Tower focuses on the Costlemark Tower that features level 50+ enemies and the chance at nabbing yourself and awesome Royal Arms weapon. Completing Costlemark Tower is one of the requirements to obtain the special key that opens the special locked doors in all dungeons.

Where Is The Costlemark Tower Dungeon

Where Is The Castlemark Tower Dungeon

How To Get Inside Costlemark Tower Dungeon

The Costlemark Tower dungeon appears impenetrable from the exterior during most times of the day. As the dungeon is inhabited by exclusively by demons, the entrance only becomes visible at night. Simply return at night and you’ll see the stairs have extended and the route through the entrance is now open. Make sure to walk over the strange object on the floor to trigger something later.

Costlemark Tower Dungeon Guide – Requirements

Costlemark Tower is one of the toughest dungeons in the game so make sure you come prepared for a fight.

  • Minimum level 50+ (higher the better)
  • 4-5x Magic Flasks filled with all elements. Bring extra Fire if you have a choice, save a Blizzard for the boss.
  • Tons of healing items
  • Ability to cure or be immune to petrify (boss battle)

Costlemark Tower Dungeon Guide – Monsters

Costlemark Tower is home to a variety of incredibly powerful enemies, most of which are demons. Some don’t have an exact weakness but in the list below containing all of the enemies we encountered, we’ve listed elements that they are not resistant too. For magic, you should typically be hitting 9999 at the moment anyway so a direct weakness isn’t always necessary.

Gelatin (Level 35)
Weaknesses: Royal Arms, Lightning

Galvanade (Level 54)
Weaknesses: Royal Arms, Guns, Machine Weapons, Blizzard
Notes: If you take too long to kill these they summon lots of Thunder Bombs. Dawn Hammer works to take them down quick.

Thunder Bomb (Level 38)
Weaknesses: Swords

Ereshkigal (Level 39)
Weaknesses: Fire, Royal Arms, Swords

Yojimbo (Level 45)
Weaknesses: Thunder

Bussemand (Level 34)
Weaknesses: Great Swords & Machinery

Red Giant (Level 42)
Weaknesses: N/A

Costlemark Tower Dungeon Guide – How To Get To The Boss

Once you reach the large, open space room with the squares on the floor. Do not activate the red switch, it will return you to the start. In the North East corner of the room inspect the glowing square on the floor to transport down to the room with the Red Giant. There’s a small hole you can crawl through here to get to the special door, but you cannot unlock that until the end of the game. Take the cube in the center of the room back up.

The next set of cubes is a puzzle. If you go in the wrong direction you will return to the Iron Giant room and face 2x Iron Giants and then 3x Iron Giants and a Nagarani, a near impossible fight at level 50. This is a really strange puzzle. I played through it several times and it felt different every time.

When you get back up take the North West most square, if it’s not available you may have to go South East again but it should be there. Take it down 2 levels. Once down, don’t go down again. Take the West cube. Kill the imps that spawn and then head South, kill the Bussemands and take the South East wall where they spawned. Then South and kill the Gelatins, then South again and kill the Bussemands, South again. Kill the Gelatins and Galvanade then East. Then click the one on the floor to go up. Kill Yojimbo.

Take the cube under Yojimbo and go back up. Kill the Imps and then take the East wall. Take down the Imps and the Galvanade and then the Southern floor, take it down twice. When you hit the floor take the Eastern wall, you’ll see a circle symbol on the floor. Kill the Bussemands and then take the floor down to go up. Follow the single path to Yojimbo with more Galvanade. Use the South wall, then East.

Drop down to kill the Gelatin. Progress, kill the Bussemands. Continue through to the boss.

Costlemark Tower Dungeon Guide – Boss Battles

Jabberwock (Level 58)
Weaknesses: Blizzard

This is actually a straight forward fight. Keep your distance and unload with Techniques and Blizzard spells. He does have an AoE Petrify that is nearly impossible to dodge so bring items with immunity if possible.

Costlemark Tower Dungeon Guide – Loot

There’s some decent loot in Costlemark, including 2 weapons that do increased damage to daemons and a Royal Arm, the Sword of the Tall – dropped by the boss.

  • Radiant Lance (On the floor in the second room past the Gelatin)
  • Thieves’ Way II (In the room with the Ereshkigal. Don’t cross the pipe, cross the ledge the opposite side)
  • The Good Chamberlain (Drop down from the Thieves Way II item and go through the large door on that level)
  • Platinum Bangle
  • Moogle Charm (Inside a room with a thunder node, the 2nd one)
  • Black Choker
  • Orichalcum (Cross over the beam near the start and check the top of the spiral)
  • Sword of the Tall Royal Arm
  • Requirement to obtain the Dungeon Seal Key that opens doors hidden in dungeons
  • Johnny Do

    Awesome job on this guide! it helped a lot!

    • Kenneth Barton

      I second that! Great guide, very helpful. 😀

  • Charles Kerr

    I did this dungeon at level 30. Minimum 50 is a lie what you should put is “Gitgud filthy casuals”

    • Skeith9

      In other words… carry 99 elixirs, phoenix downs and potions. Have the mega versions when possible. Food buffs help.

      And make full use of invincibility frames offered by link attacks, techs, item usage, recovery from danger etc etc.


      • Charles Kerr

        I did it with 30 potions, 10 phoenix downs, 30 hi elixirs. Use of gravisphere and high damage spells. The only tricky part was with the red giants and using the clever bow made it easy mode. So in other words no not cheating, I’m just more skilled than you. sorry not sorry.

        • ChrizCrozz

          Thats a damn lie.

          • Charles Kerr

            I’m doing it for a friend right now hes level 40 , I can ps4 share so I can show you plebs how its done.

          • Charles Kerr

            Took too long , I can show you a screenshot of the level, xp, And you can see the sword of the tall in the bottom right 😉 Don’t call people out just because you’re unskilled

          • Count Cid Orlandeau

            LOL playing a non competitive game and bragging about “skill” on guide comment sections. You are the definition of a snob. No its not hard, the minimum level is there for efficiency, as its really not even worth the time to do this dungeon at levels lower than 50. Sword of the Tall isn’t even worth equipping, therefore this should be one of the last Royal Arm dungeons you do, and none of the accessories you get are really that good. You wasted high level magic on an easy dungeon then told other people to “gitgud”, who are you calling a pleb? Also, no one “took too long”, they were just never gonna waste their time watching some random asshole play through a dungeon they had already beat. No one cares that you think you’re good at a single player game dude.

          • Charles Kerr


          • Insanis

            But i keep saying WHY ARE PEOPLE BRAGGING!?
            This is by far the easiest ff game i’ve ever played.
            7 yeah 7 WAS a challenge with ruby weapon and emerald but the super bosses in this game might as well be regular.
            Im not bragging im just saying there is no point in bragging in a game that’s as time consuming and as easy as this, besides who really cares?

          • Thedudeist

            the holy weapons were definitely worth my time.

          • Soot

            Then don’t believe him. I don’t and I think it’s possible.
            Judging by the pic and the way he talks, he’s an extremely insignificant small child, so he likely thinks this kind of thing matters in life.

        • Skeith9

          No. I don’t mind someone being better than me really. I am not salty or anything. I just said what I did because that is really what I believe (albeit slightly exaggerated). Also, I didnt even know there was something called gravisphere until you mentioned it just now. That black hole thingy is what it is. 😛 So thanks.

          I too, in reality use high level spells and warping to its max. But lets be honest… the i-frames are handy too.

        • Xengre

          You were using the Clever bow exploit which they fixed I believe. That is cheating. Yes, it is very easy, tho, and isn’t even hard at level 1. Magic is supremely OP in the game and you can deal with the Iron Giants + Naga very easily with some spell casts.

          You are right, tho, the dungeon is very easy. Maybe next time you can gitgud and do it legitimately.

          • Charles Kerr

            What they fixed wasn’t how I was using the clever bow. But that’s okay. Feel big about yourself for a minute.

      • Elektrolysis

        What a petty person to be boasting about something as minor as this.

    • Insanis

      Well ff15 is the easiest ff game i’ve every played i mean i killed a lvl 55 boss at lvl 23.
      Either i’m amazing or this game is easy.

  • Snowball7

    Thanks so much for this guide, Captain. Found myself doing this dungeon at 11pm last night, and was so confused by the cube puzzle! I assumed I was doing it correctly, as I was opening up new cube starting points each time, until my SECOND battle with 3 red giants, Nagarani and about 50 flans and I started thinking there must be an easier way. Luckily, Ramuh bailed me out of that and then I found your guide online and followed your nice clear instructions through the cube maze and down to the boss (which was a cakewalk after the rest!). Thanks again! 🙂

  • gsx

    In my case, it was a bit strange. When I visited the tower with Dino’s side quest active and then the dungeon quest active, the game only allowed me to activate the North West cube, which was the long maze. You get in, fight your way forward, and when the decision point comes between going East or South, you go East and that’s it.

    When I came back for the boss hunt, the North West cube was ticked but not available, and I could only proceed with the North East cube, and then the South East cube. Both lead to small mazes and then you end up in the big place attached to the locked door, and you fight one red iron giant, 2 red iron giants… the good news is that all monsters killed during the first attempt are gone, at least all monsters before the mazes / cubes.

    Only after clearing the 2 first cubes, the North West cube was again available and you do exactly the same thing.

  • Daniel Mascio

    There is also a weapon called Durandal in this dungeon. It’s a sword similar to the Radiant Lance pole arm.

  • Thedudeist

    You didnt mention missed durandal, a deamon killing sword, its by the area that looks like someone was digging a hole.

  • Thea Queen

    It’s worth noting that the information about the “puzzle” is wrong. You don’t have a choice which path you take. The only reason it appeared that way for you is because you had already “played through it multiple times”. Upon first entry you can only take the paths they’ll let you. Because of this you WILL have to fight the masses of Red Giants with Flan and whatever else they had in there.

    Also add the Durandal information. Sword is garbage, but if people for some reason don’t have their Ultima yet it might be worth using.

  • Pyrtanis

    THANK YOU FOR THIS. Seriously, this saved me from my headache getting worse with this place. <3

  • My Little Milk

    So what you’re telling me is that for this dungeon I’m in, I’m 8 levels too low and the reason I just fought 3 red giants, a Nagami thing that constantly turns my entire party into toads, and an insane number of flan because I failed a puzzle that doesn’t even seem like a puzzle. Thanks for letting me know that now, Oh and can someone quickly explain to me why there was a flash of light early in the battle? For context Gladiolus and I were toads when the light flashed, but Prompto and Ignis were dead, the flash might have triggered diologue between the characters talking about being out of the dungeon now but that may be unrelated, but for the rest of the resource consuming fight Prompto and Ignis were gone, even when I used a megaphoenix, they were alive, but they weren’t in the fight.

  • Doreen Lane

    What if you did red check point in big room who do you get to boss?