Vigilance

Vigilance is a 21-point talent in the Protection talent tree for warriors. It replaced Shield Slam, which became a standard warrior ability. It is a buff cast on other players, applied much like a spellcaster buff such as Focus Magic.

Tips and Tactics
Vigilance is best put on either the healer or a damager class which produces the most threat. It helps to have a threat-tracking addon or, if the party members don't have one, a damage meter addon so you can determine which party or raid member is producing the most threat. This will make Taunt always ready if member with highest threat outdo yours. Any tanking warrior should keep this on one party or raid member at all times.