Steam

Acquisition
Hero Skill Trainers
 * Shiloh (Sunspear Great Hall)

Trivia
This skill was originally intended to be a Guild Wars Factions skill, and the skill description was leaked prior to the second Guild Wars Factions Beta event. However, the skill did not appear in the Beta Event, or in the Factions campaign.

Unlike a certain other "Steam", this ability is likely to work whenever you use it.