Dungeon becomes available at Level 41.
Minimum gear point is 99 but this should be easily attainable with main quest pick ups and enchanting your weapon to +9.
4 Bosses, 1 of which is optional.
Basic tank and spank fights. Avoid red and keep up with your group.
BUG NOTES: There is a known issue where completion might not always award an achievement. If you've unlocked the corresponding achievement in game but not on Xbox, you'll have to wait for a fix from En Masse. There is little you can do to avoid this as well.
My recommendations are to make sure you a fresh install, fresh boot up of the game and Xbox OS, and maybe have a long ping wired connection if possible.
Comment if you have any questions. Good luck!