You must have already completed Victoria's quest "The Summoning" to collect 1000 daemon bones and have killed the Bone Daemon. The prize for killing the Bone Daemon is a golden skull. Head for the beach at the lake in the southern end of the dungeon. When you get there you should find a dark platform with a large bell hanging above it. This is the Bell of the Dead and once rung it will summon a mysterious figure known as Chyloth the Ferryman.
See Doom Gauntlet
Chyloth will yell at you a bit at first, something about only the dead may cross, but if you hand him the golden skull, he suddenly changes his mind and lets you and everyone in your party hop aboard his ferry and sail across the lake.
Summoning Chyloth without giving him a skull is not something that is advisable, as Chyloth has a very dangerous pet at his disposal. If you do so anyway, running away would be the best advice, because otherwise you might find yourself in the belly of a Skeletal Dragon.
Finally you are at the infamous Gauntlet of Doom. A place of untold riches and an untold number of dead adventurers.
Secret Mage Shop
The first thing you should do once you get here, is familiarize yourself with Nix the Variety Dealer. Nix can be found by walking through a wall in the eastern side of the hallway leading south from the beach, there he has made a small shop where he sells all manner of supplies, that could be useful to the brave adventurer.
Further down the hallway you will reach a large hall with six pentagrams on the floor, this is the center of the Gauntlet. The Gauntlet is made of a five rooms, each with a some very powerful creatures in them, the number of which depends on the number of people in there. The rooms will have to be defeated in a clockwise direction from the entrance and once you enter an active one you can only leave by death, either yours or the monsters in the room, as the doors to the room will be locked.
If you should happen to die in the Gauntlet, and you most likely will, all hope isn't lost. In the northwestern room lives a kind healer, who will help you find your path back to life for the small fee of 5000 gold pieces.
Now that you know the place a bit better, let's get on with business... The first room, which is the eastern one, is inhabited by creatures know as Darknight Creepers, strange creatures that seem to have several torsos stacked upon each other. You will have to get rid of all of them if you want to get out again in one piece.
Once the first room is cleared, you can proceed to the next one, the one to the southeast. This one is inhabited by Flesh Renderers, a type of giant insect that moves at an amazing speed and has the ability to knock you off your mount. You will have to move fast to get out of this one.
The third room is not for people who fear long sharp objects, it is inhabited by Impalers, who instead of hands have long sharp and pointy spikes at the end of their arms. A strong armor or a lot of running around is required here.
The fourth room is by many considered the easiest one, it is inhabited by Shadow Knights, a group of undead warriors who have the ability to hide and stealth around. Once they are revealed they shouldn't pose much of a threat to the experienced fighter.
Finally the fifth and final room is now open to you. In there the Abyssmal Horrors await with their powerful magic skills ready to fry you. The key to surviving this room is plenty of resistance and a lot of physical damage.
With the fifth room defeated, you should head out into the center of the Gauntlet again. Here you will find the fruit of your hard labour, the Dark Fathers. The Dark Fathers will be a battle to remember, since they are as strong as all the other creatures in the Gauntlet together and also because they have the power to summon large numbers of undead creatures to their aid.
Now that you're all done you might ask what the point of all this Gauntlet stuff is. Well isn't it obvious? Wealth beyond you wildest dreams of course. Well maybe not quite that much, but each of the Gauntlet monsters has a chance of dropping a powerful magical artifact in the backpack of one of its killers. These artifacts should make it well worth your trouble to go through all this, if you are lucky enough to get one.
Only one thing remains now and that is to leave this accursed place. Recalling or gating is out of the question since the evil of the place blocks that kind of magic, but luckily there is a moongate on the beach right next to the ferry. This moongate will take you to outside the entrance in the corrupted forest.
Use it and you have escaped your Doom.