Intimidating Shout is a level 34 warrior ability. It is an AoEfear effect shout ability which causes the target to become incapacitated for 8 seconds, although any damage will break the effect. It also causes up to 5 additional enemies within 8 yards to flee in fear for 8 seconds.
Any damage taken by the target will break the effect. The fear affecting the additional enemies is less likely to break upon damage.
This ability is possibly one of the most dangerous things a warrior can do in an instance, as more often than not feared enemies will end up triggering new enemies, and once the 8 seconds are up, the original enemies will return with help.
While soloing, it can be useful to escape if things are going badly. Using this, in combination with a [Piercing Howl], can buy the warrior enough of a head start to run clear of the fight, but this is best done in outdoor environment. In enclosed spaces, such as mines, caves or instances, it usually causes more trouble than it saves.
In PvP combat, this ability really shines - used in combination with [Charge], a single warrior can totally disrupt an enemy front line, allowing supporting ranged and pet classes to take advantage of the ensuing chaos.
Intimidating Shout can be used on a single target to incapacitate them for 8 seconds. Any damage will break the effect so use Intimidating Shout (preferably while backing out of melee range), target yourself and bandage. You can use about 80% of a bandage this way. Alternatively, use this time to gain the distance necessary for a [Charge], generating some rage, bonus damage and a usable root. In PvP, this can also be useful for tricking enemies into using their PvP trinket, wasting its cooldown.