The Fissure of Woe (commonly abbreviated as FoW) is one of the Realms of the Gods. It is the domain of Balthazar, God of War. There his Eternal warriors are in constant struggle with the Shadow Army of Menzies, Lord of Destruction. It is a very inhospitable place. Mobs are plenty and very strong. It is not recommended to go there without a full party of eight experienced players. Heroes are allowed, but henchmen are not.
After entering the Fissure you will find yourself next to Rastigan the Eternal. He will be attacked by any Shadow creatures that may find their way there. He stands no chance against them on his own, so make sure to protect him and / or clear out the immediate surrounding area of any Shadow forces before further exploring the Fissure of Woe. If Rastigan is killed, you are transported to your outpost of entry. Also be careful not to accidentally trigger the quest Tower of Courage before the coast is clear (it is safe to accept the quest, just don't attack the quest related foes). You will meet more Eternals like Rastigan in the Fissure, who must not die either.
Alternatively, you can use a Passage Scroll, which drop from Hard Modebosses; from the reward chest (for completing all Fissure quests); and (rarely) from monsters in the Fissure. The scrolls can also be purchased from Scroll Traders.
When entering the Fissure of Woe, the minimap shows unexposed regions in black and reveals them as the party explores. However, unlike most explorable areas, the exposed portions of the map are reset to black for each visit into the Fissure as if the player had never been there. The adjacent map shows the full layout and major areas of the Fissure (the teal-colored dots show the connecting paths between areas).
In general, the Fissure is divided into general areas that form an asymmetrical grid in the form:
The Fissure of Woe features several quests, which are quite demanding, but give tremendous rewards in experience points. These quests can be done repeatedly, once each time you enter the Fissure. All quests you have done on previous visits to the Fissure will be cleared once you leave it and you will have to do them again if you want to reach subsequent quests. The Obsidian armor can be crafted in the Fissure, after you have completed several quests.
The Fissure of Woe can be a daunting place for those who tread there for the first time. Here are a few FYIs to keep you alive:
Watch out for patrols!! There are patrols running around all over the place. Proceed carefully. If there are 20 yards between you and the next group, expect someone or something to walk by or pop out of the ground.
A few people should equip Rebirth. Rebirth is not useful in recovering from death situations during a fight, but it's an excellent recovery tool from near wipe out situations. The reason being that if a party is wiped out in the Fissure, it is kicked back out to the Temple of the Ages, Zin Ku Corridor or Chantry of Secrets.
Use XP rewards wisely. Players going into the Fissure are generally level 20 and do not need experience per se. Still, experience is very valuable inside the Fissure itself. Because the experience rewarded by Fissure quests is so high, it is the best tool in erasing Death Penalty from party members. As such, if a party finishes a quest and is ready for cashing in on the reward, they should save that reward until there is Death Penalty to erase.
Defend NPCs. If any friendly NPC dies, the party is booted back to the outpost they started in. Remember that this extends to unnamed NPCs like forge guards, so make sure that the area they spawn at is clear of any foes.
PULL ENEMIES. A proper puller can heavily mitigate the damage spread to the party and make even the most dangerous areas of the Fissure survivable.