I think this is what you are asking for Cartrack.

The Prerequisites for a lot of the objectives are a group of either 2 up to 5 players, thus it is better to be in a group of five(5) from the start and complete as many of the objectives as fast as you can.
The ideal situation to have Mirror Maze activated for a group of five players starting at level 70, the members of the group has to have completed all previous objectives. Note: as I stated: IDEAL Situation. Other than that, you have to complete Four Corners, and in doing so, you have to complete as many of the other objectives where you are left with three(3) objectives activated and Mirror Maze being one of them listed.
Example:
Objectives:
Face the Evil
Slash the Swarm
Mirror Maze
To complete Mirror Maze, no one in your group can go to town for any reason, thus, if a party member dies and ends up in town, you can not complete the objective. Your mission is to explore the entire Catacomb and upon reaching the last square, you will encounter the Monsters for completing Mirror Maze objective.