Activate this spell when running away. Often the attacker will be rooted and unable to follow.
This spell is also useful for gaining range against a Shaman to use Innervate.
It is entirely impractical for raiding if the druid is not a tank, given that 1) the scariest mobs are immune and 2) the Druid shouldn't aggro away from a tank, 3) the Druid is not likely to survive a single hit, and 4) a rooted mob will turn to attack other people in range, regardless of aggro, potentially killing others in addition to the casting druid. There are, however, a rare few applications, for example when dealing with blood beasts in the Deathbringer Saurfang fight.
Can also be cast in Cat, Bear, Tree of Life, and Moonkin forms.