There are two hidden switches in the castle. One is behind the throne, and another is near the skull on the counter of the Rosenqueen shops. Flip both of them to allow access to Etna's diary, which is in the middle corner of the intermediate hallway between the throne room and the shops. If you visit this area consistently for each chapter, you will be rewarded with a Testament item in the final chapter.
Unlock Majin Class
To unlock the majin class, you need each of the following classes, at level 200: warrior, male brawler, ninja, rogue, and scout. The majin is the best class in the game.
Gaining More Experience
If you want to level up faster, just throw your enemies into each other, so they will combine into bigger enemies who are worth more experience points.
How to level up faster
Once you open up the area "Cave of Ordeals". Go through it until you reach the 3rd area. Here you will find 3x3 rows of enemies and the field has a "Exp 50%" Geo panel on it. If you can use a 3x3 attack to kill all the enemies in this stage in one swoop, your character will level up insane amounts. You can take a level 1 character to level 200 if they have a high enough attack. Also be warned that the enemies in this stage have high defense, either bring out other members to weaken the monsters up or you can have one warrior bravehearted by a team of mages.
Unlocking Alternate Netherworld
Pass the Dark Congress proposal "Alternate Netherworld" to unlock the Alternate Netherworld.
Unlocking Beauty Castle
Pass the Dark Congress proposal "The Great Seal" to unlock Beauty Castle.
Getting Marjoly
To get Marjoly (Level 2500) to join your forces, beat her in the Beauty Castle.
Getting Priere on your team
To get Priere (Level 2000) to join your forces, beat her in the Alternate Netherworld.
Getting Laharl's Title
To get the Tyrant title for Laharl, beat Baal in Baal Castle.
Capturing Enemies
To capture an enemy, throw it onto the Base Panel. Then, the enemy fights against all of your remaining characters. The enemy will get some sort of boost, so its not too easy to capture. Humanoids and Bosses can not be caught. Use this to your advantage to capture strong enemies.
Easy way to kill Baal the first time
To have an easier time killing Baal, go to the map before Lord of Terror in Baal Castle. Capture a level 2500 Sert. Repeat a few times. Then, throw a Flamberg onto a Sert, and capture a level 3500 sert. repeat until you get a level 9999 sert. You will have to use the "Stronger Enemies" proposal about 10 times to get a level 9999 sert.
This will make killing Baal much easier.
Trick to kill Uber Prinny Baal
There is a simple trick to kill Uber Prinny Baal. You need a Scout or anyone with the Geo Change skill. Go to the Lord of Terror map, in Baal Castle, and have the person with Geo Change skill use it. If there are no "Damage 20%" or "Invincibility" Geo Panels, then hit "Quit" on the menu screen and try again. Keep Baal on the Damage 20% squares to have him die in 5 turns. Or, if you can do damage to him, wait for invincibility. It helps to steal Baal's items to do damage.
Get the most out of your turn
If you are trying to level all of your characters mainly by using team attacks, etc., move all your characters into position for a team attack. As long as none of them besides the initial attacker have not performed any actions, after the team attack
you can move them back to their original locations and move them again. Repeat this as desired. This also works if your characters are just out of a healers range; you can move them, heal them, then move them back into battle.
Selecting Monster Character with Little Mana
After defeating a monster it will show up in Character select. It will be selected only with lots of Mana. In order to get the Monster with little Mana, go where you can fight the Monster, and keep defeating him until its Mana cost drops to where
you can get it at your cost. Every time you defeat it go to Character select and watch the mana drop.
Unlock Mr. Gency's Exit Chapter 3
Speak to the Dimensional Gatekeeper.
Unlock Staff of Sorcery Chapter 8
Speak to Gargo.
Unlock Etna's Chamber
Speak to the skull in the shop, then speak behind the throne. Then her room will be in the corner of the next room where Ghoss and Gargo is.
Unlock God's Hand
Clear the Cave of Ordeals stage 5. Make sure you've unlocked it.
Unlock Hyperdrive Shoes
Enter the Item World B100 and defeat the Item God 2. If you exit, you must start over from B1.
Unlock Longinus Spear
No necessary Chapter: Make sure at least one of your characters has a spear mastery of 25 or higher. Enter the Dark Assembly, then speak to Longinus.