Vital Boon

Acquisition
Skill quests
 * Nightfall
 * Rally the Recruits/Take the Shortcut (Island of Shehkah)

Skill trainers
 * Nightfall
 * Tohn (Kamadan, Jewel of Istan)

Profession changers
 * Core
 * Profession Changer (Great Temple of Balthazar)
 * Factions
 * Senji (Senji's Corner)
 * Nightfall
 * Zuwarah (Command Post)

Trivia

 * The Dervish in the skill icon seems to be wielding a Hooked Scythe.
 * The functionality of this skill has changed since its introduction; see its skill revision history for details.