Persona 3 Reload

On the 91st floor of Tartarus, after you’ve fought the boss, instead of heading up the stairs to the border level (level 92), head to the right and you’ll come across another Monad Door - this one, however, is known as a Monad Passage (Elizabeth will give you a request when you’ve beaten your first Monad Door on the 80th floor).

To get access to the remaining Major Arcana (with you getting other Major Arcana tarot cards from the in-game Full Moon bosses), you need to beat the two bosses in the Monad Passage. 

Once you have, you’ll be able to open the chest at the end of the short level, which rewards you with two things:

• Temperance Tarot - which adds the Temperance Major Arcana card during Shuffle Time. The Temperance Card will increase the next Academics, Courage or Charm activity the next time you perform that activity.
• Book of Samech - which will increase the number of Major Arcana cards you can get in one day (i.e. one trip to Tartarus).

On top of that, you’ll also unlock the ‘Beyond the Darkness’ achievement. So, win-win-win.