In most eSports, competitors need to know their opponents well - the best way to counter an enemy is to know his/her strategy and prepare for all possible outcomes.

 

WoW is no different.  Most raiders are typically required to do at least a little bit of "homework" before heading into a boss fight.  This homework consists of researching one of more boss encounters in order to have a complete understanding of the boss's abilities, as well as an idea for how each part (or, "phase") of the encounters is played out.  This research comes in many forms and is often posted by other players who wish to support their fellow gamers.

 

The picture to the left is an example of how one might visually represent a boss encounter.  While such a visual representation might be limited in its capacity to demonstrate the entirety of an encounter, it is still useful for boiling an encounter down to its bare essentials and making for a quick overview.

 

For this particular fight, the image conveys what each role must do through the use of role icons; demonstrates key traps in the fight raiders must watch out for through the use of still images; and makes note of the special phase of the encounter by off-setting the description to the bottom.

 

In short, the salient details are all present for raiders who need a quick rundown/refresher of the fight.