The paths used to be Forward/Forward, Forward/Up and Up/Up, named after the directions you would pick to go while progressing through the dungeon.
When TA Forward/Up (tafu) is the path that was “closed”. Back when it was still “open” there was a complaint by a significant portion of the player base on the last boss being too hard. This was due to the last boss having an attack that would spawn adds if not dodged that could quickly grow to unmanageable numbers – and said adds not despawning if the party wiped.
While organised groups had no problems either DPSing the boss to death before the adds became a problem or dodging the attack, A.net decided to “fix” the issue by getting rid of the path and replacing it with a new path during the Twilight Assault living story.
The new path features aetherblades and scarlet and is much longer than most other dungeon paths making it not very commonly run.
The Forward/Forward and Up/Up paths still exist.
