Taught to the Hero by Patty from Stornway after you unlock the Quester's Rest as way of thanks for helping her out in The Hexagon earlier. Sluggers, Jinksters, and Sluggernauts can also use in battle this to bolster their allies, while Sluggerslaughts in high level ruins grottoes have a modified version that increases tension by two levels.
Though they can't use it in battle themselves, players can use it to help others in fights. Monsters like Bambooligans, Feralbeasts, Satyr, Bamboozlers, Abyssal octopots, Silenuses, Angora fauns, Pink bonbons however, use it in battle, with Sluggers once again using the skill.
During the climb up Cobblestone Tor, Gemma uses it while the Luminary is fighting monsters, although she wastes a turn doing so. However, it's used by Bambooligans and Bamboozlers once again to put allies in a Pep state, since tension is not in XI.