Mastering a monk is a bit more complicated. I'll try to explain all options below.

As with all other classes you need to have reached your 99'th insight
You need 200 million experience saved in your "box".
You also need the mastering items, which are Golden sand and a Cauldron

You need a certain amount of health and mana points to master, but with a monk there are two sets
of health/mana requirements. Power and Balance.

A power monk needs his health at "8850" points and his mana at "5500" points. These are significantly higher
than a balanced monk. However, the power monk will have more strength at mastery than a balanced monk. The downside
to being a power monk is buying stat points with such a high base of health. (almost 13million per point)

A balanced monk needs his health at "7000" points and his mana at "4000" points. However, a balanced monk needs to have
all his "stat's" balanced at 15 BASE per stat. This will cause him to have a significantly lower strength than a power monk,
but a balanced monks "stat" purchasing will be much lower. (almost 10milion per point)

Ok, now that you have decided what path to take to master, you have to show your skill of mastery. For monks there are 3 ways

The easiest way is getting the Brown Dugon (legend mark) and the skill "wise touch"
The most famous way is getting and mastering "claw fist"(100/100)
The hardest is to master both "beag nochd" and "puinneag beatha".

After getting all you need (as written above) you will need to head to the temple of choosing and speak with the attendant.
She verifies that you are both mentaly and physically ready for mastering and asks you for the item
Take your Golden Sand and your Cauldron and head off to the Sapphire stream where the master will craft your item, the Sand Glass.
Head back to the temple of choosing and speak to the attendant again. If she still see's you fit you will become a master, and all
the lands will hear of your accomplishments.

She will give you your Monk Master Mantle and your Kalkuri.

The Sun Bae nim Mantle.

A wonderfully crafted armour that flow's with the monks movements. It is fitted seamlessly
to a monks body.
((+1000hp, -600mp, +30% MR, -62ac, -1str/dex))

The Kalkuri.

The Kalkuri is the master monks main weapon of choice.
((+500hp, +500mp, +10dmg, +5Hit, -5AC, +10% MR, +1str +1con))

A monk can chose to empower this weapon using talos ore and a bent crux
A pure path monk will recieve a better weapon than the sub-path.
Thus i dont reccomend that a sub-path enchant his kalkuri.

And she will also teach you the Spell "Iron Skin"

Iron Skin

An improvement on the spell "dion."
This spell makes you invulnerable to any sort of attack. and lasts for a good 18 seconds.
The temple attendant needs nothing from you, but to see that you are worthy of being a master.

Now head to the oren skill master, as he will also teach you a couple of new master skill's

Whirwind Attack

A pure pathed monk skill, Whirl wind is targeted to monks with high health points.
This attack mimics the skill, kelberoth strike, in the fact that is drains your health to 20%.
However, it does not go dion. Fortunatley it is a four sided attack, that deals 20% of your health
as damage to all things surrounding you.

Triple Kick

The pure monks thrid and final attack. You have mastered your right/left combination, and now its time
to use your legs. This skill is availble to all monk master's not only the pure paths. It is very easy to
master this skill, because you already have sufficient leg power from your kick's.

After getting your proper equipment, and all your skill/spells, you will need to replace that dugon you have
been wearing all this time.
Head off to the grass fields, the mundane there needs your help in defeating some enemies.
He will ask you to defeat 2 of each kind of enemy, gather a group of friends, and defeat the creatures.
Return to the mundane and receive your Sun Bae nim Band.
((+1000hp, +1000mp, +20% MR))

Now that you are a master the true journey begins, you will face new creature's, increase your skill, defeat the creants and perhaps
one day become a druid.

Best of luck Nigma