Alright I will guide you with what I did and what you need to get to the very end.
I will try to update this constantly if I have the time. Look at the bottom to see what new things have been added.

I found out that for every member in your party that's inside the portal gets a potion called "Standard of Heroes". So if you have 4 people who are inside Tristram, the last boss will drop 4 Standard of Heroes. You can hold more than one Standard of Heroes. When you ID the Hellfire, the class skills/attributes/resists vary.
Rumor: When you have a Standard of Heroes equipped in your inventory, you will not lose experience if you die.

Here's a screenshot of Standard of Heroes.
http://i19.photobucket.com/albums/b173/Nuc...reenshot106.jpg
Here's a screenshot of Hellfire.
http://i19.photobucket.com/albums/b173/Nuc...reenshot107.jpg

Definately look at Glimjaur's + Xizeta's guide for a more in-depth story and more information about the new additions to the 1.11 patch: http://forums.d2jsp.org/index.php?showtopic=592972

Step 1:
Get these keys.
Key of Terror : Countress (in Act 1, Black Marsh - Forgotten Tower)
Key of Hate: Summoner (in Act 2, Arcane Sanctuary)
Key of Destruction: Nihlathak (in Act 5, Halls of Vaught)
There is a 1/34 chance to get these keys, so keep doing these runs until you get three keys.

Step 2:
Once you have gotten 3 keys, transmute them in the cube inside Act 5.
The first boss will be Uber Izzy, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot089.jpg
You will receive Mephisto's Brain, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot103.jpg

Step 3:
Once you have gotten another 3 keys, and after defeating Uber Izzy and having Meph's Brain on the same character.
You will have to transmute the 3 keys inside Act 5 and Uber Duriel will appear, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot091.jpg
You will receive Baal's Eye, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot092.jpg

Step 4:
Once you have gotten another 3 keys, and defeated Uber Izzy + Uber Duriel abd having Meph's Brain + Baal's Eye on the same character.
You will have to transmute the 3 keys inside Act 5 and Lilith will appear, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot095.jpg
You will receive Diablo's Horn, as shown here.
http://i19.photobucket.com/albums/b173/Nuc...reenshot096.jpg

Step 5:
Once you have gotten those three relics, transmute them in the cube inside Act 5.
Then a portal called "Tristram" will appear.
Three boss will appear, as shown under:
http://i19.photobucket.com/albums/b173/Nuc...reenshot098.jpg
http://i19.photobucket.com/albums/b173/Nuc...reenshot099.jpg
http://i19.photobucket.com/albums/b173/Nuc...reenshot105.jpg (took off game name + password for personal reasons)

Oh yea, forgot to add in. Minions keeps respawning each time you kill a group of them.
Also, you cannot create TPs in Tristram.
Baal has no extra skills, just his main ones in Act 5.
Dclone has no extra skills, just his main ones when he pops up for anni.
Mephisto has conviction and is very fast moving. So I suggest killing him last.

Tips:
1.) I think this is an obvious one, have an 8 member group. It will be quicker if you do.
2.) Characters I suggest using: A sorber (with 90 all resists), a pally with salvation (to give the group max resists), a ww barb for bo (a must have for more life/mana/defense), and hammerdins (for damage).

If you have any questions, please PM me.

Thanks to the guys who helped me on this task:
jds666
KoJ
Crust
PePiTo
PissedOffPolak
Unclepenny
Snickerfritzer
(If there's anyone who I forgot to include, tell meh )

Updated:
Tips - 08/01/05
Screenshots - 08/02/05

Future Updates:
More characters to use
What gear to use
Quickest ways to complete this

This post was edited by Cidco on Aug 2 2005 07:29pm

Great addition to my guide. And ofcourse, it was a great guide! Cheers to you Cidco.

This post was edited by Glimjaur on Aug 1 2005 06:58pm

thanks for the guide, cleared up sum questions

So who got charm and what were stats?

where is hellfire in that story ?

Information about it can be found in my guide, found here;

http://forums.d2jsp.org/index.php?showtopic=591538

i just wanted to add that i got lilith on my first transmution with the keys. so it might just be a random order that the portals open in.

Like you saw in my last s/s of Meph, I died and friends couldn't rejoin because game was glitched full.

So there's no s/s of it yet, from us.

two questions
does dclone drop annihilus in this quest?
are meph and baal beefed up like dclone?

do u need to open all portal in the same game?? cause i already open 2 with the same char and got the same thing ( meph brain) so i have 2