There are 25 levels in this dungeon and there are no short cuts to getting to the lowest level quickly.
To speed up your journey, I would suggest the following:
- Every level is the same, the only thing that changes is the layout of the bridges between platforms. You need to travel from the south east to the south west corner of the room to press a switch which opens the gate to the stairs.
- Press the back button to zoom out your mini map. On the third setting, you'll be able to see the whole level and where the bridges lie to the exit.
- Equip Turn Tail on all of your characters. If you're level 80+, you don't really need to level up any further and you can skip any fights you come across.
- By all means explore to find chests, but you don't really need to read all of the journal machines to proceed to the next level.
- Enemies won't spawn on levels 5, 10, 15, 20 and 25.
This achievement will unlock as soon as you reach level 5.