Sage Class Unlock Quest - DQ9
Quest Requirements: Defeat 5 Great Trolls with Frizz
Reward: Sage Vocation Unlocked
This is the final class unlock quest you get before the post game quest for the Luminary class. You'll find the quest on a bookshelf in Gittingham Palace L2 - North (shown in the screenshot above). When you enter the dungeon, go west and follow the path until you go up the stairs and find yourself in the L2 area.
Fall down into the hole then climb back up the stairs to find the bookshelf. If you'd like more guidance, I have maps of Gittingham Palace in my full walkthrough which you can get to by following the link. For this quest what you have to do is defeat 5 Great Trolls in Realm of the Mighty (the final dungeon) with the low level Mage Frizz spell. If you've already beaten the game and you're unable to figure out how to get back to this dungeon - check the end of this guide for more details on that.
I've found that the best spot to farm these trolls is in the western hallway on floor L8. A screenshot of the location I am talking about is below, the trolls in this area and on L9 too it seems have a much higher chance of spawning.
They have about 800-850 HP in total so what you'll want to do is each battle damage them with your group until you've inflicted about 700 damage. At this point you'll want to start using Frizz on your Mage until the troll is defeated. That's literally all there is to it!
Once you're done the quest you'll have to return to Gittingham Palace to turn it in.
Reaching Realm of the Mighty After Beating the Game
In order to get back to Realm of the Mighty during post game you'll want to first complete Side Quest #039 and acquire Sterling's Whistle. This will allow you to summon the Starflight Express from anywhere on the world map - aside from letting you fly around the whole world map this vehicle also allows you to go to the uncorrupted version of Realm of the Mighty.
While flying go to Disembark but instead of Disembarking select 'No'. When you do this Sterling will then ask you if you wish to travel to the Realm of the Mighty, select 'Yes'. This is how you get to Realm of the Mighty. Once you're here in order to get to the "corrupted" version of the zone you will want to venture all the way up the light path and speak with Celestria at the top. She's able to teleport you to the version of Realm of the Mighty with these Great Troll enemies.