quoted from maplesea.com

1. 
   Once the player has received these two items, he/she needs to go back to their 4th job advancement NPC, which he/she will be rewarded with a Skill Book that teaches them Maple Hero.
2. Clicking on the NPC a 2nd time will change the player into their 4th job proper.
   Most 4th Job skills have to be obtained by doing quests (for example, fighting monsters to get "Summon"). Some of the skill quests require you to get a certain one of a kind item to activate them, and some of the more valuable skills have to be learnt from a skill book.
3. Also after getting a skill, you are only able to put up to 10 skill points into it. This will happen regardless of what the max level is. You will be able put more points after you get Mastery Books and succeeding them. There are different Mastery Books for each skill and there are two versions
   Lv 20 Mastery Book: This book requires a minimum of lv 5 in that particular skill to use
   Lv 30 Mastery Book: This book requires a minimum of lv 15 in that particular skill to use.
   These Books have a success rate (70% for level 20 Mastery Books and 50% for level 30 Mastery Books).
4. The Books do not damage your character in anyway if they fail, but a new one will be needed.

10m mesos~! i think it's something 'cheap' and 'affordable' for most mapleRs~ you may choose to pay the 10m mesos if you thing that hunting is a difficult job~!

which way of getting the quest items would you choose? hunting wise/ mesos wise?!

let's go into the skills after your 4th job advancement.!! ^^

Hero-warriors's skill

4th Job Advancement - Available Skills:
Maple Hero (all class)- Increases all stats by 10% for 600 seconds.
Hero's Will (all class)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Monster Magnet (all warriors)- Will draw one monster within 200 range in front of you with 95% success rate at max.
Stance (all warriors)- At max, 70% chance of not being knocked back for 300 seconds.
Charge (all warriors)- Can charge through 15 enemies with 130% attack power.Only works when monsters are in front of you.
Achilles (all warriors)- Reduces physical damage by 15%.
Blocking (Hero and Paladin only)- 15% chance of blocking enemy attack and knocking them back. 2 seconds of invincibility upon activation. Only works when a shield is equipped.
Brandish - Does 260% damage 2 times to 3 enemies (Brandish's damage calculations are one swing and one stab).
Advanced Combo Attack- Must have Combo Attack (3rd job skill) maxed. Attack power 150%, max combo increased to 10 with 60% chance of adding 2 combos with 1 hit at max.

white knight:

Fire Charge
Power Strike: 312% DMG to enemies without weakess, 468% to enemies with weakness
Slash Blast: 156% DMG to enemies without weakness, 234% to enemies with weakness
Charged Blow: 300% DMG to enemies without weakness, 450% to enemies with weakness

Ice Charge
Power Strike: 273% DMG to enemies without weakess, 409.5% to enemies with weakness
Slash Blast: 136.5% DMG to enemies without weakness, 204.75% to enemies with weakness
Charged Blow: 263.5% DMG to enemies without weakness, 395.25% to enemies with weakness

Thunder Charge
Power Strike: 325% DMG to enemies without weakess, 487.5% to enemies with weakness
Slash Blast: 162.5% DMG to enemies without weakness, 243.75% to enemies with weakness
Charged Blow: 312.5% DMG to enemies without weakness, 468.75% to enemies with weakness
(Explanation: Base dmg% (260% Power Strike, 130% Slash blast, 250% Charged Blow) * elemental charge DMG % (120 Fire, 105 Ice, 125 Thunder), * 150% for elemental advantage)

Paladin
4th Job Advancement - Available Skills:
Maple Hero (all class)- Increases all stats by 10% for 600 seconds.
Hero's Will (all class)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Monster Magnet (all warriors)- Will draw one monster within 200 range in front of you with 95% success rate at max.
Stance (all warriors)- At max, 70% chance of not being knocked back for 300 seconds.
Charge (all warriors)- Can charge through 15 enemies with 130% attack power.Only works when monsters are in front of you.
Achilles (all warriors)- Reduces physical damage by 15%.
Blocking (Hero and Paladin only)- 15% chance of blocking enemy attack and knocking them back. 2 seconds of invincibility upon activation. Only works when a shield is equipped.
Holy Charge/Divine Charge- Gives weapon a holy element along with 140% attack power for 300 seconds upon maxing.
Advanced Charge- At max, increases Charge Blow damage to 350% with 100% chance of not losing element upon using Charge Blow. This is a passive skill.
Blast - A stab attack that doesn't dispel element.Unique for each charge. Does 550% damage. (The damage calculations for Blast is random between Stab/Swing.)
Sanctuary - Summons a golden hammer to attack up to 15 monsters. Does 900% damage. Cool-down time: 100 seconds.How ever it cannot kill a monster.It will reduce it to 1 at the best.

Dark Knight

4th Job Advancement - Available Skills:
Maple Hero (all class)- Increases all stats by 10% for 600 seconds.
Hero's Will (all class)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Monster Magnet (all warriors)- Will draw one monster within 200 range in front of you with 95% success rate at max.
Stance (all warriors)- At max, 70% chance of not being knocked back for 300 seconds.
Charge (all warriors)- Can charge through 15 enemies with 130% attack power.Only works when monsters are in front of you.
Achilles (all warriors)- Reduces physical damage by 15%.
Berserk - At max, When HP is below 40% the attack power will increase by 200%.
Beholder - An active support skill that heals/buffs the dark knight according to the skills below and gives +20% Mastery. 20 minute duration.
Beholder: Heal Mastery - Heals the dark knight 500 hp per 4 seconds when Beholder is active.
Beholder: Buff Mastery - Increases weapon attack, accuracy, avoidability, defence or magic defence per 10-30 seconds interval when Beholder is active. Each buff lasts for 100 seconds

Fire/Poison Arch Mage
4th Job Advancement - Available Skills:
Note
All MP costs and spell power without calculating Element Amplification
Maple Hero (All Classes)- Increase 10% of all stats at max for 600 seconds.
Hero's Will (All Classes)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Mana Reflection- (All magicians) At max has 60% chance of reflecting 200% of the magic attack that hit you. This skill do not reduce damage done on you.
Big Bang (all magicians)- 450 magic attack (max) with 80% mastery. Has to be charged before use.
Infinity (all magicians)- 40 seconds without using mp, cooldown of 10 minutes
Paralyze- 210 magic attack power with 60% mastery. Has a chance of turning the enemy into stone for 15 seconds.
Elquines- Summons ice monster with 270 magic attack that freezes for 3 seconds hitting up to 3 enemies. Duration of summon is 160 seconds at max.
Fire Demon- At max, magic attack of 120, 60% mastery that pierces through 6 enemies and continues to damage enemies for 15 seconds, enemies are only weak against ice during the scorching.
Meteo- Using 3500 mp at max, damages 15 monsters with a 570 magic attack power as a whole screen attack.

Ice/Lightning Arch Mage
(Only available in Korean, Japenese, And Recently Taiwan MapleStory 4th Job Advancement - Available Skills:
Note
All MP costs and spell power without calculating Element Amplification
Maple Hero (All Classes)- Increase 10% of all stats at max for 600 seconds.
Hero's Will (All Classes)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Mana Reflection (All Magicians)- At max has 60% chance of reflecting 200% of the magic attack that hit you. Cannot reflect above 200% of enemy's max hp.
Quatum Explosion (all magicians)- 450 (max) magic attack with 80% mastery. Must charge.
Infinite Mana (all magicians)- 40 seconds without using mp, cooldown of 10 minutes
Ifrit - Summons fire monster with 300 magic attack that can hit up to 3 enemies for 160 seconds at max.
Ice Demon- At maxed, magic attack of 100 60% mastery that pierces through 6 enemies and continues to damage enemies for 15 seconds. Enemies are weak against fire during the freezing. It also freezes non-ice monsters for 3 seconds.
Blizzard- Uses 3500 mp at when skill is max; damages 15 monsters with 570 magic attack power.
Chain Lightning- Character emits lightning from the tip of wand/staff and the lightning travels to a nearby opponent. Once the lightning reaches opponent, it will travel to the next nearby opponent. 180 magic attack power with 60% mastery. Power reduce by half as hits through monsters.

Bishop
(Only available in Korean MapleStory) 4th Job Advancement - Available Skills:
Maple Hero (All Classes)- Increase 10% of all stats at max for 600 seconds.
Awake (All Classes)- A probability of escaping from certain status effects. Cool-down time: 10 minutes
Mana Reflection (All magicians)- At max has 60% chance of reflecting 200% of the magic attack that hit you. Cannot reflect above 200% of enemy's max hp.
Big Bang (All magicians)- 450 (max) magic attack with 80% mastery. Must charge.
Infinity (All magicians)- 40 seconds without using mp, cooldown of 10 minutes
Bahamut - Must have lv15 summon dragon (3rd job skill). At maxed, dragon lasts 160 seconds and can attack up to 3 monsters with 230 magic attack power.
Holy Shield- All party members will not be affected with status ailments for 40 seconds at max. Cool-down time of 120 seconds.
Resurrection- Revives members. Has a 30 minute cool down time.
Angel Ray- A upgraded version of holy arrow. 240 magic attack power with 60% mastery.
Genesis- Uses 3500 mp at when skill is max; damages 15 monsters with Holy damage and has 670 magic attack power.

Bow Master
(Only available in Korean MapleStory) 4th Job Advancement- Available Skills:
Maple Hero (All classes)- increases all stats by 10% for 600 seconds.
Hero's Will (All classes)- a probability of escaping from certain status effects. Cool-down time: 10 minutes
Sharp Eyes (All Bowmen)- at max, gives everyone in party 15% chance of performing a critical attack that does 40% more damage for 300 seconds. Unlike normal critical, it does a multiplication instead of adding 40% more damage.
Dragon Pulse (All Bowmen)- at max, 100% attack power (if not charged. Attack will increase if charged) with 100% knock back to a far distance and will go through 6 monsters. With minimum range. 100% knock back even at level 1, though only 4 monsters.
Advanced Bow Mastery- upon maxing, gives 90% mastery with +10 attack power (yes, it is passive). Must have Bow Mastery (2nd job) maxed.
Phoenix (Summon)-You must have silver hawk at least lv15. For 200 seconds,the hawk will attack up to 4 enemies with the base power of 550 at level 1 and with fire attribute. Does not stun. Does not critical.
Hamstring- at max, has 60% chance of decreasing 5 enemies' speed by 60 for 180 seconds.
Hurricane- A Bow Master exclusive skill that costs 9 MP per arrow, and each arrow does 100% damage. Once button assigned is held down, it can continuously fire arrows like a machine gun until button is released.(Do not underestimate this skill, it can shoot about 7-9 arrows per second,which makes it faster than night lords triple throw with shadow partner which shooting time ,hitting time and cooldown time takes abount 1.8 seconds) However, pots cannot be used until the button is released.
Concentrate- For a brief time, you can raise your attack and lessen your MP consumption. At max it raises weapon attack by 26, mana consumption becomes 50%, and it lasts 180 seconds. However, it has a cool down time of 6 minutes.

Crossbow Master
(Only available in Korean MapleStory) 4th Job Advancement - Available Skills:
Maple Hero (All classes)- increases all stats by 10% for 600 seconds.
Hero's Will (All classes)- a probability of escaping from certain status effects. Cool-down time: 10 minutes
Sharp Eyes (All Bowmen)- at max, gives everyone in party 15% chance of performing a critcal attack that does 40% more damage for 300 seconds. It multiplies your damage instead of adding additional damage. For instance, a Bow Master using Strafe could hit up to 13k per arrow, but only 3000~5000 for non critical.
Dragon Pulse (All Bowmen)- at max, 100% attack power (if not charged. Attack will increase if charged) with 100% knock back and will go through 6 monsters. Even at level 1, has 100% knock back but only for 4 monsters.
Advanced Crossbow Mastery- upon maxing, gives 90% mastery with +10 attack power (yes, it is passive). Must have CrossBow Mastery (2nd job) maxed.
Freezer (Summon)-Level 15 Golden Eagle required. For 200 seconds, Freezer will attack up to 4 enimies with 500 base power with ice powers. Has been given the freeze effect but will not critical.
Snipe - Snipe a target with a killing shot.(which means it is able to kill an enemy in a hit regardless of its hp(does not work on bosses) Cooldown time : 15 seconds,also, when it is used on bosses it does 100k dmg. Note: It will always be a critical.
Blind - puts enemy into darkness any time you damage them whether it be smashing them with your cross bow, using strafe, or your Freezer attacks at 40% success rate.
Piercing - 850% damage that will go through up to 6 enemies. Takes 2 seconds to charge. Skill will release once hit. Comparable to the Crossbowman's Iron Arrow, although instead of losing power as it passes through monsters, Pierce grows stronger.

Night Lord
(Only available in Korean MapleStory) 4th Job Advancement - Available Skills:
Maple Hero (all class)- adds 10% to all stats for 600 seconds.
Hero's Will (all class)- a probability of escaping from certain status effects. Cool-down time: 10 minutes
Showdown (all thieves)- for a certain amount of time, exp rate, drop rate, and monster's defense power will increase by 40%. Works only for 1 monster at a time.
Fake (all thieves)- 30% chance of totally evading monster's attack (passive). A block of wood will appear when this skill is activated and character will automatically smile.
Venom (all thieves)- All attacks will have a 30% chance of putting the monster in a state of poison for 4 seconds. Also increases your magic attack by 60.
Ninja Ambush (all thieves)- summons fellow ninja and attacks with 125% attack power for 12 seconds to any monsters within 150 range.(max 15 monsters)
Ninja's Dance-a meelee attack that either knocksback monsters or sucks them in.
Spirit Javelin - sacrifices 200 stars to have unlimited stars for 120 seconds. Similar to an Archer's Soul Arrow, Spirit Javelin will "create" an imaginary slot of stars to draw from, with the Weapon Attack of the active throwing stars at time of casting..
Triple Throw - throws three stars with 150% damage each.

Shadower
(Only available in Korean MapleStory) 4th Job Advancement - Available Skills:
Maple Hero (all class)- increases all stats by 10% for 600 seconds.
Hero's Will (all class)- a probability of escaping from certain status effects. Cool-down time: 10 minutes
Showdown (all thieves)- for a certain amount of time, exp rate, drop rate, and monster's defense power will increase by 40%. Works only for 1 monster at a time.
Fake (Bandit version)- 40% chance of totally evading monster's attack (passive). A block of wood will appear when this skill is activated and character will automatically smile.
Venom (all thieves)- at max, all attacks will have a 30% chance of putting the monster in a state of poison for 4 seconds. Also, it somehow increases your magic attack by 60. This is a passive skill.
Ninja Ambush (all thieves)- summons ninja warriors and attacks with 100% attack power for 12 seconds any monsters within 150 range.
Assassinate- Must be in dark sight upon activation. Attack increases as the length of time spent under dark sight increases. Attacks 3 times, but a 4th attack is triggered with a certain success rate. At max, has a base damage of 120% with a 90% chance of unleashing the 4th attack with 250% damage. Only increases the damage after entering dark sight. Damage will not further increase after going into dark sight for more than 18 seconds.
Smoke Bomb- for 60 seconds, all party members cannot be damaged within a range of 200. Cannot use for 10 minutes upon activation.
Boomerang Step- attacks up to 6 monsters twice with 500% damage each.

for the full details of these informations.. visit~http://strategywiki.org/wiki/MapleStory/Jobs