Only 30 persons can pass to the next level, and they will be awarded with experience worth of two EXPballs.
-After you done killing monster in second room, Hell Cloister has came.
You have to choose between Left Flank and Right Flank. Each Flank has 12 spawns of Wraith. (Killing them you may get a NightDevil book)

This room it is a Work Team room, you have to cooperate with other player and kill the Wraith same time till you reach the amount to decreases the certain level.
After that you will be sent in Ultimate Pluto's room.
The winners in this pass will get experience worth of three EXPballs.
-Ultimate Pluto's room: he is protected by Syrens. Kill all of them first, and then
Ultimate Pluto will emerge. Kill him and get a Dark Horn.
This is a free PK map, you won't get PK points.
The winner who has the Dark Horn will be awarded with experience worth 5 EXPballs.

4. UnknownMan Quest:
The Unknown Man, in fact, is incredibly well-known for his ability to eat Dragon Balls and give you experience!
First of all, you need 1 Dragon Ball (if your character it is under level 100) or 2 Dragon Balls (if your character it is above level 100).
Find the Unknown Man in the Market. He will beg you to give him 100 silvers, after that, he will ask you to buy a flagon of Drunk Celestial wine.
Buy the drunk celestial wine from the Shopboy in Twin City.

Go back to UnknownMan and he will beg you for Dragon Balls and DrunkCelestialWine, after he eats the Dragon Ball he will give you Experience.

5. Eat EXPball:
Each day you can eat 10 EXPballs.
From where you can get EXPballs:
Join Lottery by using 27 CPs, and maybe you will find in one of the boxes EXPball or you can buy them from Shopping Mall for 27 CPs each.
After you will have the EXPball right click on it and you will get Level or Points, depends on each person's level.

6. Equipment Bonus Quest Series:
Well not so long time ago, CO Crew Member made a quest called Equipment Bonus Quest series, this is a the best idea, because it helps new comers to get some better gear (free items) and level up faster.
I love this quest because after you do the NPCs mission you get some parts of an EXPball and after you exchange the bag to your trainer he will give you one more EXPball.

So there is what you need to do:
First of all go at your Trainer Job, depends on each profession/class what you are, talk with him to give you a task.
After you took the task, follow the instruction of the NPC to make the quest, he will put you to kill some monsters, visit his friends or buy something from him, after you done that he will tell you that you done the quest and he'll get a reward for you.
When you done the quest, your TrainingBadge will transform UltraBadge, your trainer will help you to find what reward is hidden in UltraBadge, for sure you'll get one item and one EXPball.