The Dungeon Journal (briefly named "Encounter Journal" in build 14107) is a new in-game tool planned to be released in Patch 4.2. Despite its name, it is really more of a boss and instance info tool, providing mapped location, ability, phase, and loot information for bosses and general trash mob loot info. It will also include add info with their abilities. There are no pre-requisites to use it and it can be viewed anywhere. It will not include strategies for dealing with boss abilities, but will include some background lore.
Most likely, not all bosses or dungeons will be included in the initial release. As of build 14313, 5-man dungeons and 10/25-man raids were split in to different panes. Some idea of what will be available should be available on the PTR. A good guess would be that all 0400 Cataclysm instance and boss info will be available at first with other instances and bosses appearing in future content patches.
A: The Dungeon Journal is a new piece of UI in World of Warcraft that players can use to find out more about specific dungeons, and the bosses within those dungeons, including what abilities they have and the rewards they offer.
Q: How will I access it?
A: While in a dungeon, hitting "M" (the default key for Map) will open the Dungeon Journal. A new button will also be available in the navigation tray. The Dungeon Journal can be accessed from anywhere - in a dungeon, in a raid, on a boat, etc.
Q: Will I have to experience a dungeon or encounter in order to see the associated Dungeon Journal content?
A: There won’t be any "gating" or limitations placed on what content a player can see in the Dungeon Journal. All boss/dungeon/raid information will be available to all players regardless of level, gear, or content experience.
Q: What will it show me?
A: The dungeon/raid map will display the locations of each boss in their respective locations, marked by unique icons.
Players can access boss information by clicking on boss icons on the map, or by clicking on the boss’ name in the associated tab of the dungeon/raid map page.
General loot information for the dungeon/raid can also be accessed from the dungeon/raid main page by clicking on the Loot tab. This will show all loot dropped - from bosses and trash - in the instance, of a certain quality.
Boss abilities will be available via the boss’ page, either by clicking on the map or by going through the Dungeon tab. The Dungeon tab on the boss’ page will list out all major spells, abilities, and phases for that fight.
Q: Are the descriptions going to be simplified or detailed?
A: Descriptions will be verbose and complete. Our goal is to give a lot of context to the abilities in terms of how they’ll play out; however, we will not be giving any strategy tips in the Dungeon Journal. For example, while the Dungeon Journal might say something like "This ability will cause all players in the affected area to take damage," it won’t say anything explicit like "All players except the tank should stand behind the boss during his Shield phase."
Q: Will this include adds?
A: Yes. If a boss has adds, like Ascendant Council or Erudaxx, their abilities will be listed, too.
Q: What bosses will be included in 4.2?
A: That's still being determined. We want to include as many as possible and add more as we go along. We'll provide additional information on availability as we progress through the Public Test Realm process.
You mistake this implementation as a walk-through. While you will be told the items and abilities the boss will employ, it will not tell you when, how much damage, where to stand etc. This is merely an extra in-game tool to help players get into the encounters, understand them a little better, and enjoy them. The ability to take down the boss is still soundly within player hands and abilities.
I wanted to come back to this thread to update and clarify some information that I provided previously on how much information we plan to add to the Dungeon Journal. We actually do plan to provide specific information on the abilities and damage that will be done as well as information on the phases. We will not, however, be providing any strategies on how to defeat the bosses. That will be solely up to you to figure out. We hope that by providing this information in an easily accessible way, that it will help people be able to spend their time in game actually taking on these encounters more than spending it out of game doing research.