* Talk to Maat as a level 66 or higher Bard, Beastmaster, Black Mage, Dark Knight, Dragoon, Monk, Ninja, Paladin, Ranger, Red Mage, Samurai, Summoner, Thief, Warrior or White Mage to receive this final test. He will ask you to bring him a testimony of your job. These are dropped by various mobs depending on job.
* Once you bring Maat the testimony while as the corresponding LV66+ job, he will challenge you to a fight to prove once and for all you have ultimate mastery over your job. You will be warped to the BCNM area after a confirmation.
Note: After defeating Maat for the first time, it is no longer necessary to go to Maat in Ru'Lude Gardens prior to attempting another fight; in fact, you must proceed directly to the appropriate burning circle to trade the testimony to for subsequent fights. After beating Maat for the first time (on any job), he will no longer warp you straight to the BCNM.
* Trade your testimony to the BCNM entrance point, again while as the corresponding job, and select the "Shattering Stars" arena to enter the fight.
* Your sub-job is disabled for this fight. It is advisable to go to the BCNM using a sub that will enable you easy transportation out after you (hopefully) win, such as /BLM.
* Maat assumes your job and has all the abilities of it including your 2-hour. However, Maat will always use Hand-to-Hand attacks and associated weapon skills, including some special abilities of his own.
* You have 10 minutes to beat Maat. Note that any time taken with preparations you make after entering the BCNM but prior to engaging Maat still counts against you.
* Maat will not attack until you do. Use this to your advantage by buffing yourself appropriately, possibly resting to full before fighting (but be careful not to take too much time), and if applicable, engage him with an attack that is easiest/best performed on a non-aggressive enemy, such as Sneak Attack. Note that even if he's not attacking you yet, Maat will still use any available magic he has (depending on job) to buff himself as well. (Red Mages in particular should beware of this)
* If you have never defeated Maat on any job before, you will not lose Experience Points in this fight upon death. However, after you have managed to win at least once, Experience Points will be lost upon defeat in subsequent fights, even on different Jobs.
* If you succeed, you will receive a scroll of Instant Warp, unless you already have one in your possession/storage, or you have already defeated him previously - in which case you will get nothing.
After the Fight
* Talk to Maat again in Ru'Lude Gardens to complete the quest. If you have beaten him before, you do not need to do this.
* Maat only needs to be defeated once to break the cap to 75 for all jobs. However, in order to receive Maat's Cap, you must defeat him on all 15 pre-ToAU/WotG jobs.
* Subsequent battles (after this quest is completed) can be fought uncapped. The level 66 minimum still applies.
Class specific walkthroughs ans Source: http://wiki.ffxiclopedia.org/wiki/Star_Breaker