Notice: Watcher will be discontinued starting from the Midnight expansion.

Blizzard is set to no longer provide addons access to aura info (buffs/debuffs) nor the combat log starting with Midnight in a battle against addons like WeakAura's and DBM.
When this happens, this will make it impossible for Watcher to function. Making Watcher work has already become increasingly complex because recent expansions do funny tricks with spells that the addon API does not talk about, requiring manual code just for those cases, but with Midnight it will actually become impossible for Watcher to track your rotation.

As a result, Watcher will sadly have to stay behind in TWW. Be prepared to say goodbye to the addon as it will not be making it into Midnight. 🙁

Introduction

Rotation Watcher helps you manage your rotation by consolidating and condensing information onto a simple to read display. It allows you to focus on things that are more important like boss mechanics, your situational awareness, or listening to your raid leader; instead of being bogged down in the act of performing your rotation.

With deep and powerful configuration options, Watcher allows you to see exactly the information about your rotation that you want to see. Properly configured and customized, Watcher is a mighty tool for both new players just learning their classes as well as players that have been raiding since classic.

A GIF of Rotation Watcher running on a 2H Frost Death Knight:

Rotation Rotation Watcher also includes:

A dynamic event-driven architecture; unlike some other rotation helping addons, Rotation Watcher won't tank your framerate
Masque support for skinning icons
A large number of visibility options to control exactly when Rotation Watcher shows up
And more!

Description

Through the use of a priority system as well as powerful filters for spells and abilities, Rotation Watcher displays your rotation in the familiar context of a timeline, with higher priority spells stacked on top of lower priority ones and upcoming abilities placed on the timeline according to when they will become useful. Abilities on the timeline are waiting for a wide variety of things: coming off of cooldown, waiting for resources, monitoring a DoT, etc.

Configuration

A slightly old full walkthrough of Rotation Watcher configuration is located here

Display settings documentation.

Spells can be configured to be cast based on a wide variety of filters whether that be the presence (or lack there of) of an aura on you or your target, your target's health percent, your mana/resource percent, whether a spell can be stolen or interrupted, whether you have a particular talent or glyph, among other options.