Act 2 Quest 6: The Seven Tombs - Diablo 2
Quest Location: Canyon of the Magi/Tomb of Tal Rasha
Quest NPC: Jerhyn
Quest Goal: Place the Horadric Staff on the Orifice; defeat Duriel
Reward: Able to progress to Act 3
Flag:Able to progress to Act 3
The Seven Tombs is the final quest in Act 2 and arguably the most well known. For this quest you'll need to find the "true" Tomb of Tal Rasha which you can identify by the marking on the stone pillars outside of it. Open your quest log ingame and click on this quest to learn what mark is the right one. This mark changes each time you create a new game and you can check your quest log to see which mark is the real one.
Note: In this instance 'make a new game' means when you log out and back in, a new play session if you will. Not when you start a new character.
Doing what's called 'Tomb runs' is the best way to level a character from 15 - 25 in the game. These runs involve clearing every single Tomb of Tal Rasha and then resetting the game once they're all cleared. Players typically avoid killing Duriel as he is just a waste of time if your only goal is for EXP. For more information about Tomb Runs check out my Diablo 2 Leveling Guide - Tomb of Tal Rasha runs.
Inside of the real Tomb of Tal Rasha you'll find the Orifice which is where you'll need to place the Horadric Staff to complete the first part of this quest. In order to obtain the Horadric Staff you'll need to complete Act 2: Quest 2 The Horadric Staff. Once you place the staff where it belongs there will be a brief scene where everything shakes and a hole is blasted into the wall.
Killing Duriel is all that's left of this quest and Act 2. For the most part this fight is a tank and spank; if you can't tank and can only spank then kite Duriel around his room. The room is quite small but you can manage, Duriel can be slowed on every difficulty so that'll make it easier.
A tip if you're struggling is to stock up open up in town before the fight with Duriel on Potions and drop them in clusters in his room at the start of the fight. You can easily run over to them and pick them up - this is easier than using them out if your inventory since when you pick them up they're added directly to your Potion Belt.
Duriel is probably the least farmed boss in all of Diablo 2 mostly because he can be rather time consuming to reach once you have already completed Act 2. When you're unable to check your quest log anymore to determine the true Tomb of Tal Rasha, you'll have to go to where The Summoner is in Arcane Sanctuary first.
The Summoner has a set of symbols behind him (pictured below); the true Tomb of Tal Rasha's symbol is always missing from the floating symbols. In the case of the screenshot below, you can tell that the one missing is the one I am standing right next to with a circle on top and a half circle below.
If you are having trouble remembering all of the symbols, use the markings on the ground next to Horazon's Journal (pictured above). All 7 symbols are shown on the ground here, all you have to do is cross reference and check to see which one is missing to determine the true Tomb of Tal Rasha.