Omen is a threat meter. Basically, enemies in WoW decide who to attack by deciding who is the most threatening based on the abilities you use. What Omen attempts to do is provide reasonably accurate estimates of your group's relative threat level on individual enemies, so that you can see when you're in danger of pulling aggro (or, if you're next on the snack list if your tank bites it). This info is usually only critical in raids, where only tanks can survive aggro, but it's useful for any multi-player situation.   

Omen is an interface for the Threat-2.0 library, and comed bundled with it.   

The latest updates are always available at files.wowace.com, or through the WowAceUpdater.   

Do other people need Omen installed for it to work?   
Short answer: yes   

Long answer: kinda   

To get fully accurate data, your groupmates must have Threat-2.0 (or an addon that uses it) installed and running. Any addon that uses Threat-2.0 will satisfy this requirement and will provide full and accurate threat data to Omen.   

If you or your groupmates have any of these addons installed, or have Threat-2.0 installed as a standalone, then they are capable of sending and receiving threat data.   

Please note that unlike Threat-1.0, Threat-2.0 DOES NOT have KLH Threat Meter interoperability.   

Do I need to install Threat-2.0 to use Omen?   
No. Threat-2.0 comes bundled with Omen as an embedded library. You only need to install Threat-2.0 if you want to provide your group with threat information without a GUI. As a user, you can think of Threat-2.0 as a stripped down tank version of Omen.   

How does Omen handle multiple targets with the same name?   
Joyous news! Thanks to upgrades Blizzard made in 2.4, Omen can now tell every mob apart. You should have accurate threat information for every mob you engage, regardless of its name.   

What else has changed?   
Omen has a number of display modes now. You have:   
The "Single Target" mode. This is your standard threat meter mode.   
The "AOE" mode. This shows your relative threat on all targets you are in combat with. Useful for seeing your relative threat on multiple targets.   
The "Overview" mode. Shows people who are currently high on threat on any enemy you're in combat with.   
The "Healer/Tank" mode. Shows each of your tanks' targets (pulled from oRA2 or the Blizzard tank settings) and their threat lists.   
Single-bar customization is not in yet. This is coming.   
Pullout bars are not implemented yet. This is coming.   
Where do a report a bug?   
(todo, for now, use the message board here, the wowace forums or #wowace on irc.freenode.net)   

Where do I make a feature request?   
(todo, for now, use the message board here, the wowace forums or #wowace on irc.freenode.net)   

No changes   

Table of Contents
1 Installation Guide   
2 Translations   
3 TOC Numbers (Out of Date Mods)   
4 Mac Support   
5 Directory Structure   
Installation Guide
Exit "World of Warcraft" completely   
Download the mod you want to install   
Make a folder on your desktop called "My Mods"   
Save the .zip/.rar files to this folder.   
If, when you try to download the file, it automatically "opens" it... you need to RIGHT click on the link and "save as..." or "Save Target As".   
Extract the file - commonly known as 'unzipping'
Do this ONE FILE AT A TIME!   
Windows   
Windows XP a built in ZIP extractor. Double click on the file to open it, inside should be the file or folders needed. Copy these outside to the "My Mods" folder.   
WinRAR: Right click the file, select "Extract Here"   
WinZip: You MUST make sure the option to "Use Folder Names" is CHECKED or it will just extract the files and not make the proper folders how the Authors designed   
Mac Users   
StuffitExpander: Double click the archive to extract it to a folder in the current directory.   
Verify your WoW Installation Path
That is where you are running WoW from and THAT is where you need to install your mods.   
Move to the Addon folder   
Open your World of Warcraft folder. (default is C:\Program Files\World of Warcraft\)   
Go into the "Interface" folder.   
Go into the "AddOns" folder.   
In a new window, open the "My Mods" folder.   
The "My Mods" folder should have the "Addonname" folder in it.   
Move the "Addonname" folder into the "AddOns" folder   
Start World of Warcraft   
Make sure AddOns are installed   
Log in   
At the Character Select screen, look in lower left corner for the "addons" button.   
If button is there: make sure all the mods you installed are listed and make sure "load out of date addons" is checked.   
If the button is NOT there: means you did not install the addons properly. Look at the above screenshots. Try repeating the steps or getting someone who knows more about computers than you do to help.   
Translations
When you download a mod, please be sure that the mod is compatible with your translation of wow. Some mods only work on the US versions, while some only work on some of the various European versions. These variations are called "Localizations".   

TOC Numbers (Out of Date Mods)
When Blizzard patches WoW, they change the Interface number. This means that all mods will be "out of date" unless or until the author releases a new version for that interface. Some people go into the .toc files and update the numbers themselves, but this is STRONGLY advised against as it will cause problems locating possible incompatibilities addons. When you log into WoW after a patch, you DO NOT have to delete your interface directory. All you have to do is simply tell WoW to ignore the interface numbers and load all the mods anyway. All you have to do is, while at the "character select" screen, look in the lower left corner and click on the "addons" button. A window will pop up listing all your installed mods.   

If you look in the upper left corner of that window there should be a box that says "Load Out of Date AddOns". You want to CHECK this box. Now simply go into WoW normally and all your mods should load. As of the 1.9 patch, you will have to do this after EVERY patch/update that Blizzard posts! If you encounter any problems with a mod after a patch, please be sure to let the author of the mod know so they can fix it.   

See also: About "Out Of Date AddOns"   

Mac Support
WoW addons are not platformed based. As such, they can be used on either Mac or PC. You can extract both .zip and .rar files on a Mac using StuffitExpander.   

Directory Structure
World of Warcraft
      |_ Interface
          |_AddOns
              |_*AddonName*
                  |_ *AddonName*.toc
                  |_ *AddonName*.xml
                  |_ *AddonName*.lua
                  |_ (possibly others as well)...