A simply guide to doing the class changes at lv 20 and lv 60.

Lv 20 Class Change

Level requirements: 20
Hardest for: Mage or Archer (Reason: Low HP)
Easiest for: Clerics (Reason: Heal)

First off, talk to the appropriate NPC, and begin the initial quest. Youll have to find a key: Just go kill some Ratmen. It drops from anything. Literally. 

Once you get it, return to do the quest, but wait: Go in prepared. 
First, get a buff from a lv 47+. This may require you to go to Elderine first. 
Second, scroll up. T1s will do just fine. 
Third, get some pots. Any kind will do, tho I prefer T1. 
Lastly, take off all your armor. Thats right. Take it off. 
Talk to Sean to begin your class change. 

Once inside, your Shadow will appear, talk for a bit.. (during this time, you should be putting your armor and stuff back on). youll notice your Shadow has no armor, and no weapon now, because it mirrored you when you walked in: and you had no armor or weapons on. 

Wail away at your double. Soon it should spout some nonsense and run off. A blue light leads your way. Follow it. Kill everything in your path. When you reach a room with a locked door, kill everything, then the door will open. Follow the path again, but this time, when you enter a large dark room, stop. Go to the other side, and look in the corners. You should find a Shadow Marlone and Shadow Mara waiting silently for you. Kill them now. Otherwise they show up at the end. 

Once done, continue on. When you approach a crystal, be ready to run back out as soon as the lights start coming back on. Your Shadow appears and talks. Ignore him when he hits you. Go back down the stairs outside the room, and around the lip of the door frame. In this position, just right, the stone monsters cannot hit you, but your double is close enough that you can hit him. So ignore the stone golems and attack your Shadow. (If you cant get it to work, dont worry about it, attack the stone mobs first, then attack your Double, theyll return, and just repeat the process). 

Tada! Youre done. Go talk to the appropriate NPC, and change classes. You may now wear all 1-58 armor for your class. 

Lv 60 Class Change

Level Requirements: 60
Hardest for: Clerics (Reason: No Aggro pulling attack)
Easiest for: Mages, Archers, Fighters (Reason: Aggro pulling aoes)
First off, talk to the appropriate NPC. 
For now, you can survive with just a buff, but I recommend getting a buff, and some T3s just in case (Fighters can go with just T1, clerics should have a FULL set of T3, including any str pots they have). +9 weapons, especially for clerics, are a good deal, so even if you have to borrow one, do so. 

Sean will ask you to take an object to Roumen, but wait, do not hit a scroll. Instead, click OKAY or SURE, or ROUMEN, and he sends you to Roumen himself. Youll notice a lot of "NPC" characters with weird names. Ignore them for now. Talk to "Romulus". Lights will flicker and the "NPC"s will turn into Zombies. Kill them all. A timer will tell you how many are left. 

When time is up, youll be ported out. 
Talk to Sean again, but this time, DO NOT hit "Okay" or "Roumen". Hit the cancel button or whatever there is. Then click your own Roumen scroll. Once at Roumen, go talk to Romulus. He will tell you some yimmer yammer. Hit the confirm choice. Youll then be sent to..

The second part. First off, listen to the Joker ramble on, then once hes done, pick a Die, and hit the Spinner. Its all chance. If it doesnt land on your Die, then kill the Mini Trumps and try again. 

Repeat this until you "win". 

When you win, follow the Joker’s lead into a second room. He will then shut the doors. You must kill him. So do so. Hes not very hard at all. Once done, make sure to pick up the Time Piece he drops. Youll be ported back to Roumen, at Romulus, where you can do part three. 

This is the third part, and the hardest. Even if you think you might not need them, go ahead and put on those T3. If the first and second parts took you too long, get a rebuff too. Put on any additional pots you think you might want (but dont worry about poisons and stuff, you wont encounter that). 

Once you confirm with Romulus, it sends you to a new map that looks like AEW. Follow the path to the right, and on the right youll find a big open area (where right now the red trumps and trees are in the real AEW), where Hero Roumen and Elf Chief Elderine wait for you. 

Here is the hard part. Spawns will appear and attack the two Heroes. 
Regardless of your class, here are some overall tips:
- Roumen can take about 2-3x as many mobs/dmg as Elderine
- The Heroes heal when they are not attacked. 
- If Elderine is attacked for too long, she will begin running away. Chasing after her when she does this can be a real hassle, so deal with the mobs on her first. 
- Its a good idea to aim for Elderines mobs twice, then Roumens once, changing between them every so often so that each has a time to heal. 
- You cannot heal the Heroes (clerics)

If you are an Archer, Mage, or Fighter: Continue reading. 
If you are a Cleric, skip down to the cleric section.
-Archers, Mages, and Fighters-
Archers: rely on your aoes. 
Mages: rely on your aoes.
Fighters: rely on mock and aoe stun.

For mages and archers: I recommend you stand on the fire, and overlook the entire area. Use your aoes to pull mobs to you, or simply aoe where the heroes are. Youll easily pull aggro and save the heroes. 

For Fighters: I recommend you mock whichever mob you want: the one going for Roumen, or the one after Elderine. Either way: use your aoe stun on the ones on Elderine since shes the weakest of the two. 

Should be easy for you. 

-Clerics-
Rely on rejuvenate, and your only two attack skills.

First off: Get rid of heal. 
Yes. 
Take it completely off your skill set. In its place, put rejuvenate. Throughout the entire part of the quest, do not use heal. Only use Rejuvenate to lock whatever aggro you get. 

Secondly, this requires a bit of speed. When the spawns appear, quickly get between Elderine’s attack mob, and her. Theyll initially go for you. Hit rejuv to lock your aggro. Pick off the ones attacking Elderine by using Bash and Trip/Bleed. Use 1 skill per mob. When you have no skill, hit them about 2-3 times. Youll find out how many is just right. But you need to hurry, because Roumen is dying as we speak. 

Head to Roumen and do the same to his mobs. Remember to spam Rejuv to keep aggro. You may / may not kill the mobs each time, but if you keep them on you, youll be ok. 

Repeat this. As time goes on youll find it harder and harder, but keep up with it. Remember: Spam Rejuv. Keep an eye on their HP and make sure the heroes have enough time to heal. Use HP regen pots, and your rejuv to stay alive. Oftentimes, towards the end, youll find the only way you win is simply because time ran out. Most likely you wont finish killing the mobs.

Credits go to RikoRain.