Catacombs

The Catacombs is a series of levels called "floors" which are repeatable and significantly harder to progress and have bigger skill gaps. Currently, you need to obtain Story Dungeon Levels to access The Catacombs. The Levels are shown below.

Entrance - Level XV

Floor 1 - Level XXX AND PREVIOUS FLOOR COMPLETION

Floor 2 - Level L AND PREVIOUS FLOOR COMPLETION

Floor 3 - Level LXXV AND PREVIOUS FLOOR COMPLETION

Floor 4 - Level C AND PREVIOUS FLOOR COMPLETION

Floor 5 - Level CL AND PREVIOUS FLOOR COMPLETION

Floor 6 - Level CC AND PREVIOUS FLOOR COMPLETION

Floor 7 - Level CCC AND PREVIOUS FLOOR COMPLETION

Floor 8 - Level CD AND PREVIOUS FLOOR COMPLETION

Floor 9 - Level CDL AND PREVIOUS FLOOR COMPLETION

Floor 10 - Level D AND PREVIOUS FLOOR COMPLETION

Floor 11 - Level M AND PREVIOUS FLOOR COMPLETION

Floor 12 - Level MM, PREVIOUS FLOOR COMPLETION, AND A CATACOMBS KEY.

It takes a while to unlock Catacombs Floor 12, let alone beat it. It is incredibly difficult. It will take months to complete. It is incredibly complex and dangerous and you may need to beat it a few times to obtain the best items to make it easier. So far, that is the max amount of Catacombs floors available.