To begin Locke’s sidequest, simply travel to and enter Maarport. Once you do, go a bit southwest from the main entrance to trigger a scene. Locke will break down a bit and mention to go see Zemrode, which isn’t possible, so the backup is someone named Alcon, who is in the imperial palace. Luckily, you don’t have to go searching for Alcon in the populated areas, as he can be found in the throne room. After a scene, he will mention someone named Raggys in Wyllia, so get back on your winger and fly there next.
If it isn’t day time, then sleep at the inn and exit it for a quick scene, then make your way to the house in the northwest corner of the village, next to the bridge you use to cross into the northern part of the continent. There will be another scene just outside of the building, then you’ll return to the inn. Once you regain control, visit the beach in the northern part of town and speak with Glink, who is near some trees more towards the eastern end of the beach. Speak with him and it looks like you’re heading to Scar Top next. Save before you enter, as you will be facing a boss in the very first area.
BOSS - Gravell
This overgrown boar is similar to Alpsy, who you fought in Mistral Gorge towards the beginning of the game. Just like with the former boss, Gravell will attempt to clump up your characters by using Breath In, then use Head Charge to deal massive damage to your party, as well as Headbutt. This damage can be increased even more if it buffs itself with Muscle Flex (physical attack/defense up). Fang Bite is a two-hit attack that only hits in front of it, so you can avoid that by staying away and/or to the sides. Lastly, Menace will remove all of your ATB gauge, and there’s nothing you can do about it.
If you remember how you fought Alpsy back in the beginning of the game, then you shouldn’t have any trouble with this iteration. Your melee characters should be on the sides of Gravell, while your ranged characters should be out of direct line of sight. Whenever the boss does Breath In, then you’ll need to reposition your party members. Other than that, the usual strategy of debuffing the boss’ strength (Kanata’s Calamity or any skill you have with Physical Mar attached to it) and healing when necessary.
Once you win, watch the scenes (there’s a lot of talking) and you will end up back in Wyllia (even more conversation), where Raggys will hand over the Raggys’s Spritnite. You can take this to any magic consortium to unlock the Burst Shot skill spritnite. As with the previous sidequests, you also unlock the ability to create Burst Shot with memories.