Phoreus Test Area is a group mission somewhat similar to the Nedder Test Area. Once inside, players will find themselves in a room with six evenly spaced doors leading to the various trial chambers.
Terminals to the right of each door will allow a player to unlock a single door of their choosing. After opening a door, the other doors will be unable to be opened until that trial is complete. The door opens to a short corridor with another door leading to the arena room itself. Once battle begins, the doors seal shut and cannot be opened again, which can quite easily strand players who didn't make it into the arena. Due to this system, if the entire party is killed, the doors remain shut and cannot be opened, which can leave the players with no reward.
A terminal in the central room where players spawn and are resurrected has an exit feature which triggers mission completion. If any of the six rooms have been completed, the party will get rewards proportional to the number of completed rooms when any player uses the exit terminal. Players may still individually leave via the F11 option.
Note that leaving via the exit terminal resets the reward for Phoreus Test Area when you return to the Divine Observatory, so if you wish to re-attempt the mission for the same reward, it is advised that you leave by using F11 and not the exit terminal