Copperbell Mines Hard Mode is an end-game dungeon that players use to farm Tomestones of Mythology; you earn 50 for completing it. You will also get 100 Tomestones of Philosophy for your efforts. The dungeon becomes accessible upon completion of the main scenario quest Out of Sight, Out of Mine.
Below is a detailed boss guide for each of the three bosses within the dungeon. Between bosses is straightforward clearing trash monsters.
Hecatoncheir Mastermind
This boss can be a pain. Not because it is difficult but because there are bomb monsters that spawn that can easily wipe your group if you do not kill them fast enough. These are called Flamebeau and there will be three of them.
When Hecatoncheir Mastermind uses an attack called Darkfire it will cover a portion of the battlefield in fire, and standing in it will do damage to you. This means the group must constantly be ready to move along the platform. It is when Darkfire is used that the Flamebeau will appear. Kill it quickly before it explodes.
The rest of the adds on the platform should be prioritised before dealing damage to the boss, but not ahead of the Flamebeaus. The boss itself is fairly simple; just avoid standing in front of it if you are not tanking it.
Gogmagolem
Gogmagolem is an interesting fight in that the idea is for you to kill it via means other than normal attacks. It is very similar to the Ichorous Ire fight in the original Copperbell Mines in that you make use of a Blasting Device to attack the boss.
You should decide which of your DPS players will operate the Blasting Device. The other will be killing the Kindling Sprites that spawn around the room. Since the Sprites spawn in different places it is best to have the ranged DPS on these so that they do not have to move. They have low HP and the tank does not have to worry about them.
For the player operating the Blasting Devide they must interact with it for a Waymaker Bomb to spawn. The player must then run over and pick up the bomb. Once picked up they run over to the boss and place it near it before it explodes. This will do around 30,000 damage to the boss. Keep doing this until the fight is over.
Once Gogmagolem has died a spriggan called Biggy will spawn. He has low HP and will die quickly via normal attacks, but be aware of the bombs around the room and avoid their explosions.
Ouranos
Ouranos is the last boss in Copperbell Mines Hard and it is important to understand the mechanics of the Sand Worm creature that spawns early into the fight. But to begin with the tank should tank the boss in the centre of the sand area, with everyone else (except melee DPS) outside of the sand area. Melee DPS should stand behind the boss.
A ranged DPS player should prepare themselves to handle the Sand Worm. You will notice there are Crystalized Rock objects dotted around the room. These are food for the worm. When the text “The abyss worm is searching for fodder” appears on the screen you should pick up a Crystalized Rock and place it on the sand. The worm will then come and eat the rock. It is important that the worm is fed otherwise it will use a high damage attack called Bottomless Desert. Players should also avoid standing near where the Crystalized Rock was placed.
Apart from this, be aware of Gigas adds that will spawn occasionally throughout the fight. These should be killed and are not something the tank needs to worry about. The rest of the fight is just throwing damage at the boss until you win.