As all Full Moon Operation bosses, its appearance and behavior are based on Tarot cards from the Major Arcana in the reverse position. The Priestess means someone with knowledge and wisdom, yet the reversed version of it means someone unable to use that knowledge or someone not able to make decisions. Thus instead of confidently standing like the priestess does in the upright position, it instead lays on the ground sloppily.
The B and J on her breasts are taken directly from the Tarot card. They represent Boaz and Jachin, two copper pillars, which stood in the porch of Solomon's Temple.
The Arcana Priestess takes over the train and attempts to cause a collision with another train. This is based around the conflict of intellect and instinct the card represents, which is shown with the Black and White coloration of the Shadow.
The entity has the appearance of a young woman wearing only the bottom half of a dress, her whole body is covered in either white or black, with the letters B and J on her breasts. Her hair looks like scrolls with text written on it, which are stuck to the wall not allowing anyone to pass. She wears a red, butterfly-like eyemask on her face, indicating her Priestess arcana. She herself sits inside the train on the floor with her legs spread out. She also seems to be abnormally tall at full height, even when compared to other Shadows
After reaching the monorail's end they find a huge Shadow that has taken over the monorail, but after defeating it the monorail won't stop, leaving the protagonist to use the brakes manually, saving both Yukari and Junpei.
Persona 3 Reload[]
The timer functions practically the same way: the only exception is that although it starts at 30 minutes, based on how much of Arcana Priestess' HP has been depleted, the timer will automatically go down by 15 and 7 minutes consecutively, reducing the actual time limit for beating the boss to roughly 8 minutes. The only major difference is that the timer starts when facing the boss.
There is a time limit of 8 real-life minutes for the team to both reach the boss encounter from the 3rd to last cabin and defeat it at the end of the monorail. Therefore, it is not advised for the player to take too much time at the Shadows in front of it or stay idle in the cabins, or they might end up having not enough time to defeat the boss. In harder difficulties, the time to cross the train and defeat the Priestess becomes shorter.
The battle has a time limit of 30 minutes. If the boss's HP drops to 50% and 30%, it will use Invitation to Chaos to cut the remaining time by half.
On the first turn after its HP is reduced by half, the boss will summon a Despairing Tiara to the left and a Loathsome Tiara on the right. In subsequent summons, it summons a Skeptical Tiara.