So you have reached 99, however there are several more obstacles one must overcome to be dubbed a Master. This first of these obstacles will be to train Maiden Trap 90/100 and Peek Maxed.
The base requirements for a Rogue Master is 4250hp and 2200mp. Make sure you have this requirement before you continue. You may ascend to achieve this base, please look at the Ascension section of the site to find helpful ascending information.
Finally you will require two items that can be hunted in deep Cthonic Remains: Copper File and Smith's Hammer. After you have achieved all these requirements you may start your Mastership.
You will get to a point where she asks you to see the Fae in 20-1 East Woodlands to construct the Fae's Flute. Head to East Woodlands and she explains that you will require the Copper File and Smith's Hammer to construct the flute. If you already having these items, just speak with her again and she will give you the Fae's Flute.	Return to the Temple of Veil and she will dub you a Master (after taking your experience).
You will notice that all your spells and skills now have a mastering ability of 100. You will also be given your Master Equipment. For the stats on these items please check them out in the Rogue Armor and Rogue Weapon sections.
To recieve your Master Hat: Shadow Mask , you'll have to participate in the Goblin War at the Grassy Fields outside Loures Castle. Just enter and kill two of each type of Goblin. Once you have finished return to the Loures Guard in the Grassy Fields to recieve your Hat.
Finally you will also be given the skill "Assassin Strike" which is a powerful single massive attack skill, and "Midnight Slash" which is another assail. Right now you will want to head to Oren Skill Master and speak with the him for your other master skills "Stab Twice" and if you are pure you will receive "Shadow Figure" as well. More information on these skills can be found in the Rogue Skill section. Congratulations on Mastering!
Now that you are a Master you may Empower (pure) or Enchant (sub) your Hy-Brasyl Azoth. To start this you need to talk with the Tagor Wizard. He will explain to you that you will need a Crux . So firstly you will need a Bent Crux and a Talos Ore which can be found in low level Chaos, creatures here will drop the ore and crux.
Once you get these go to the Abel Armorsmith and he will fix your Bent Crux into a Crux. After you have your Crux, return to the Tagor Wizard and he will replace your weapon with an Empowered Version if you are a Pure Rogue, or an Enchanted Version if you are subbed. Information about these weapons can be found in the Weapon section.
You may also retrieved your Master Item from the Unknown Depths-Gem Ore Quest. For Rogues you will receive the Ruby Whip. You may get more information on this quest and the items in the Quest Section and Equipment Section of the web site.
Now that you are a master you may Buy stats. To do so go to the Temple of Choosing and speak with the attended. She will allow you to trade 150Hp points for one stat of your choice. You may repeat as long as you do not go over the Maximum allowed of that stat in your class, and you do not go under the Base Requirements for Health of your Mastership. For Rogues your Max stats are: 180/100/100/150/215.