Location: Boklad
Petitioner: Jachym, Scholar
Unlocked: Complete most of Onward
Reward: The Breath of Earth (Upheaval), 20 Wyrrite, 30 Renown
In order to unlock this side quest you must first complete almost all of Onward, a main story quest that will take you to the border town of Boklad. This involves completing two sub-quests and retrieving a Trader's Pass from some bandits. Once you have the Trader's Pass you're meant to speak to Goetz in Boklad. At this point you'll unlock three side quests in Boklad, including Onward to Discovery.
The petitioner for this quest is Jachym, a scholar, and he's sitting on a bench across from Boklad's Obelisk. He needs to hire a fighter to help him investigate some nearby ruins, and Clive fits the bill. Jachym will rush off as soon as you agree to assist.
Follow the scholar south of Boklad, to the Steps of the Forgotten. Shortly after leaving town you'll find Jachym being attacked by a group of Ne'er-do-wells. They're melee opponents, and no big deal. You'll receive Steelsilk, Magicked Ash, and a Gil Bug for winning the fight.
After discussing the nearby ruins Jachym will, again, run off. Follow him south and you'll find the scholar on the road to Laetny's Cleft, this time waylaid by a group of Goblin Roughhousers. This lot has magic users with them, making the goblins a bit more of a threat than the previous bandits, though... not by much. You'll receive Wyrrite and Magicked Ash for winning the fight.
Off he goes again. Follow Jachym into Laetny's Cleft and it won't be long before you're facing off against a group of Wandering Echoes (Fallen Hunters) and a Wailing Echo (a Fallen Guardian). The Echoes are just mooks, but the Guardian is a full-on miniboss with some strong medium- to long-range moves. You can negate its reach advantage by staying in close for the majority of the battle, only ducking back when it starts up an AOE attack.
You'll receive Wyrrite and Magicked Ash for winning the fight against the Echoes, and the quest will end.