The northern desert is a dungeon where only spell casters should prevail. It is unlocked by completing the bank quests.
Monsters: All unlocked monsters and desert trollsBosses:
Special Rules: Whenever you kill a monster it will remove nearby water tiles.
Recommended Classes: Wizard, Sorcerer
The boss will either have very high damage or physical resistance, so naturally you want a class that can fling a bunch of fireballs. The three best suppliers of this requirement are the spell casting classes. Wizards, due to their inexpensive spells, Sorcerers, due to their extra mana, and Bloodmages, but due to the fact you won't get them before you do this dungeon (probably) I won't include them. Naturally, you're going to want to avoid mana burn, as it will hurt these classes. If the Aequitas is the boss, you should probably go wizard, as their hit-spell-hit combo is ruined if you can't take a hit from the boss.
If you are playing as a Wizard, it is fairly straightforward. Go around converting glyphs, to max out your mana, and killing higher level monsters. When you are level 7 or so, and a few experience from level 8, begin fireballing the boss. When you run out of mana, kill an enemy to level up. Continue fireballing, using potions if necessary. This is extremely easy, and you don't need a mid-fight level up. Feel free to use melee in addition to fireballs if it is the Tower of Goo or you can survive a hit from Aequitas.
If you are playing a sorcerer, find BURNDAYRAZ asap and do a hit-spell-hit combo on a level above you. Convert glyphs whenever you find them to get your mana to 18 and then 24. Continue doing hit-spell-hit combos on higher level monsters until you are level 7. When you are level 7, and a few exp from level 8, hit the boss. Fireball him until you can't fireball anymore. Kill a lower level monster to level up. Continue to use the hit-spell-hit combo, using potions if necessary, until the boss is dead.
Note that this dungeon can easily be completed by non-mage classes, but they are recommended. If you do approach this dungeon with a melee specialist class like Monk, Warlord, or Paladin, bringing the Really Big Sword as a preparation is advised. This will give you a tremendous damage bonus against physical-resist enemies.
The only quest in the Northern Desert is Desert Rose which requires you to beat it with both the wizard and sorcerer.