Nagafen's Lair  

Reffering to Kiros's post below, in my opinion this one of the best places to fight in your 40s. I'm always encouraging people in my guild to go here starting at their upper lvl 30s. I have always preferred fighting in dungeons versus wide open areas. This may be due to the fact that I'm a Cleric and can't solo like many classes can in wide outdoor zones.

The best thing about this zone is that the camps are divided pretty equally. I mean this exp wise, not referring to loot. The lowest part of the dungeon is the pool/window part. You will only be fighting the Kobolds which are under lvl 40 but give good exp till 48 or so. 3-6pp average on loot, throw in FS weapons and bronze armor you'll find yourself encumbered with lots of goodies to bring to the gypsy vendor just outside at the druid rings. The Kobolds can be troublesome when you get adds but as long as you have a group averaging around lvl 40, you'll be fine even without an enchanter. Also there are 2 zones you can run to very quickly from the Window room.

The next camp up would be the King room or KPC as its called on Terris Thule. My best memories of ever fighting in dungeons came from this camp I think. You're fighting the same old Kobolds but there are 3 rare mobs that are part of this camp. On average you should get at least one of them to pop an hour. There is the:

Kobold Champion: Lvl 39 Warrior mob. Hits hard but not substantial hp. Drops the no drop Painbringer (rare) and the Shield of the Slain Unicorn (common)

Kobold Priest: Lvl 39 Cleric mob. Can heal himself very well. Keep him stunned. Drops Carnal Pauldrons (common) and Mithril Breastplate (rare)

Solusek Kobold King: Lvl 42 Shadowknight. Easily the hardest spawn in this camp. Comes with skelly pet. Drops the no drop Fleshripper and Runed Mithril Bracers. The RMBs seem more common.

There is also the Kobold Noble. He is not neccesarily part of this camp but if he's up, he's up for grabs unless anyone is specifically camping him alone. He's a lvl 39 Enchanter. He can and usually does charm your tank. Drops Petrified Erudite Heart and Staff of Writhing.

The next camp up are the bats and bugs. You usually need a group of mid 40s to do this camp but its possible with lower lvls. The rare mobs around here are:

Death Beetle: Lvl 42. Average hp for its lvl but hits hard. Drops Black Chitin leggings.

Nox Spider: Lvl 44. Hard hard hard. Drops Green Chitin Bracer and Green Silken Drape.

Stone Spider: Lvl 45. Very magic resistant. Drops Brown Chitin Protector and Crystalline Orb.

These are the main exp camps. Next up are the Fire Giants, Efreeti, and of course the fire dragon Lord Nagafen.

Hope this helps. Good luck to anyone going to this great exciting dungeon.