This is a quick and easy method in Nightmare to Powerlevel yourself from level 30 – 40 in Diablo 3 in a little over an hour. You should get some decent gear and and 32-37 get gear that grants extra experience. You can get +10 – +18% experience items for most of your slots and only spend 50 – 70k on it. Since it’s part 5 of Act 1 you will probably be around level 32-33 when you get here.
So what you wanna do, is when you get to Nightmare mode. Get to Part 5 The Broken Blade. Once you are on the Broken Blade quest, continue until you are in the Crypt of the Ancients. When you enter you will get a checkpoint.
Kill everything in the Crypt and be sure to get the Enlightened Shrine if it is there for extra XP. It’s a tiny dungeon but has a lot of mobs so also try to get Massacre Bonuses. I’ve gotten bonuses for killing up to 55 mobs here (2200xp). Don’t pick up the quest item. When you have killed all the mobs, log out and resume game and you will be right back at the entrance with a full dungeon.
The Crypt of the Ancients takes 1 – 2 minutes to complete and gives a whopping 15k – 40k XP depending on bonuses. So leveling from 32/33ish to 40 takes only a little over an hour and then you are ready to steamroll over the next parts of Nightmare. If you want leveling here 40 + is also still very fast.