Completing the optional "Deep in the Valley" quest in Phantom Blade Zero is crucial for accessing a large portion of the game's initial zone. The quest begins shortly after players leave the Outpost and proceed north, where they will encounter an NPC guarding a locked gate. This NPC has lost the key, tasking the player with its retrieval.
The Sha-Chi Tower Base Camp Gate Key is located at the very top of the Sha-Chi Tower, near where players encounter the Friendly Shadow Warden. However, the key is inaccessible until players acquire a specific weapon: the Hunter's Chain Sickle. This item is obtained after defeating The Hunt, a boss encountered during the game's campaign. Once this boss is defeated, players should return to the top of the Sha-Chi Tower. A prompt will appear allowing them to use the Hunter's Chain Sickle, functioning as a grappling hook, to reach the uppermost ledge and retrieve the key.
With the key in hand, players can return to the previously encountered gate. Although the NPC will be gone, the path through the pass is now open. Venturing "Deep in the Valley" yields various rewards, including upgrade materials. Additionally, this area contains a Lóng Pillar leading to a challenging boss fight and herbs required for Yu’er’s Apprentice Healer quest. Players can also explore the furnace area of the Sha-Chi Tower, where a lift may be discovered that ascends to the Crimson Manor. Exploring these areas as they become available is recommended to advance certain quests and world states within Phantom Blade Zero's first region.