The Big Barrel Bomb, Sonic Bomb, and Flash Bomb are useful combat tools in Monster Hunter Stories 3: Twisted Reflection. These items can interrupt monsters, deal heavy damage, and help complete certain quests more easily.
However, players cannot craft them right away. To unlock their crafting recipes, they must complete the A Rocky Past side quest, which is part of Kora’s questline. This mission becomes available early in the game and takes players through a cave dungeon filled with monsters and environmental obstacles.
Once the quest is completed, the blueprints for these bombs become available for crafting.
How to Start the A Rocky Past Quest
The A Rocky Past side quest becomes available during Chapter 1. To begin, speak with Kora in Azuria Castle.
Kora is a geologist who studies caves and rock formations. She asks the rider to explore an uncharted cave connected to her research. This quest is also the first mission in her small chain of side stories.
After accepting the quest, the next objective is to travel to the cave entrance located southwest of Azuria.
Find the Cave Entrance
The cave is located on a small island in southwest Azuria.
The fastest way to reach it is by using the Broadleaf Basin Catavan Stand and traveling northeast. The quest marker will appear on the map with a yellow icon, making the entrance easy to locate.
Once inside, the quest turns into a short dungeon crawl filled with environmental puzzles and monster encounters.
Explore the Cave
Inside the cave, players will encounter several blocked passages, breakable walls, and monsters guarding different routes. Progress mainly involves breaking obstacles and clearing enemies along the path.
Break the Blue Crystals
Early in the cave, a path is blocked by blue crystals. Use Rathalos and its ranged attack to destroy them.
Breaking these crystals clears the route and often rewards players with materials such as:
Stone
Pelagicite Ore
Earth Crystal
These materials are useful for crafting later in the game.
Break the Cracked Wall
After the first area, players will reach a chamber with orange crystals. On the right side is a cracked wall that can be destroyed using ranged attacks.
Beyond the wall, the cave splits into two paths.
Monster Hunter Stories 3: How to Get Big Barrel, Sonic, and Flash Bomb
The left path leads to a battle with Yian Kut-Ku, while the right path contains a roaming Velocidrome.
The main route to progress the quest is through the left side.
<span class="BZ_Pyq_fadeIn">Tip</span>
Cracked walls still appear on the mini-map, which makes them easier to locate. Orange crystals usually mark the correct path forward.Follow the Left Path
After defeating the Yian Kut-Ku, continue forward and destroy the stone barriers blocking the path.
Soon the player will reach a shallow water area. One route leads to an optional fight with Anjanath, which can be skipped if the goal is only to finish the quest.
To continue the main objective, break the cracked wall on the right and climb the yellow wall using Tobi-Kadachi.
Further inside the cave, players will encounter Bnahabra. Instead of fighting them in turn-based combat, they can be eliminated quickly using ranged attacks.
Continue climbing the yellow walls and following the orange crystal markers deeper into the cave.
Enter the Underground Water Area
Eventually, the path opens into a flooded cavern where Ludroth patrol the area.
Players can either fight them or avoid the monsters and move through the water. Using a monster that can swim will make this section faster.
Swim through the left opening, destroy another cracked wall, and proceed into a larger cavern.
Before entering the boss room, it is recommended to save at the nearby Catavan Stand.
Defeat the Gypceros
The final encounter of the quest is against Gypceros.
Gypceros is known for its flash-based attacks and poison abilities, so players should focus on breaking its head and maintaining pressure with strong attacks. Once the monster is defeated, the A Rocky Past quest is completed.
Monster Hunter Stories 3: How to Get Big Barrel, Sonic, and Flash Bomb
Rewards From A Rocky Past
Completing the quest unlocks the crafting recipes for several useful combat items:
Big Barrel Bomb – Deals heavy damage and is great for setting traps or finishing weakened monsters.
Sonic Bomb – Forces certain monsters out of hiding or interrupts underground behavior.
Flash Bomb – Temporarily blinds monsters, making them easier to control in battle.
These items become craftable once their blueprints are unlocked, allowing players to bring them into future hunts and quests.