Chapter 5: Flaming Mountains contains a Secret Area in Black Myth Wukong. This secret area is called Bishui Cave. To reach it you must complete the Ox NPCs questline to find all five Element Carts.
Follow the steps in this order:
Step 1: Defeat Pale-Axe Stalwart boss
Chapter 5 > Woods of Ember > Ashen Pass I: From this shrine go to the next corridor where a lot of bulls and undead soldiers are fighting. A miniboss will spawn here called “Pale-Axe Stalwart”. Defeat him, then talk to him until he repeats the same line of dialogue. He gives you the quest to find all Five Element Carts in Chapter 5.
Step 2: Defeat Crimson-Silver Cart (after Emerald Hall)
Chapter 5 > Furnace Valley > The Emerald Hall: Automatic story-related boss, unmissable, found on main path up the stairs after Emerald Hall. On the way to this cart you will automatically have to defeat two other carts “Brown-Iron Cart” & “Gray-Bronze Cart”. You can’t miss any of them, these 3 carts are all story bosses, beating them is mandatory to advance on the story path. If the Ox is there to join you in the fight, exhaust all dialogue with him afterward. If he’s not there, proceed to step 3.
Step 3: Talk to Pale-Axe Stalwart again at first location
Chapter 5 > Woods of Ember > Ashen Pass I: Return to where you first met the Ox, exhaust all dialogue. He will now move to the spot where you defeated the Crimson-Silver Cart after Emerald Hall. (If he’s no longer at the first spot proceed to Steps 4-6)
Step 4: Talk to Pale-Axe Stalwart where you defeated Crimson-Silver Cart (after Emerald Hall)
Return to where you defeated the third cart “Crimson-Silver Cart”. Pale-Axe Stalwart will be there. Exhaust all dialogue. (If he’s not there check his next location and first location again)
Step 5: Find the fourth Element Cart
Chapter 5 > Furnace Valley > Valley Entrance: From this shrine walk down the path, then enter the lava pool on the right. Go to the corner of the lava to find an Element Cart stuck in the lava, surrounded by a bunch of enemies (the cart won’t attack you). Interact with the cart to pull a string. Exhaust all dialogue with it.
Step 6: Find the fifth Element Cart “Rusty-Gold Cart”, talk to Pale-Axe Stalwart at his last location
Chapter 5 > Field of Fire > Fallen Furnace Crater: From Fallen Furnace Crater turn around, backtrack down the path where the big ball was rolling earlier on the way to this shrine. Halfway down the path, on the left, the rolling ball will have destroyed a barrier. You can now go down the left, follow that new path to reach Flint Vanguard boss. After him go down further until you reach the shrine “Cooling Slope”. After this you will see a big frozen gate. Go near it to spawn the final element cart “Rusty-Gold Cart”. It will injure the Ox NPC. After defeating the cart, talk to the wounded Ox NPC who will be sitting on the right side of the frozen gate. Afterward you can interact with the Frozen Gate, follow the linear path behind it until you get a cutscene that teleports you to the Secret Area “Bishui Cave”.
Is this quest missable in any way if I don’t follow the proper order?
Not missable. I did it after the story myself.
So i pulled the string for the cart before i did all of the other steps because i was curious. Now, after defeating the bronze cart there is no string to the fourth cart. Am i locked out of the quest or should i just keep closing the game and running back?
You don’t have to pull that string again. Just talk to Ox in all places mentioned in the guide and then go to the shrine Cooling Slope. The last cart will appear there.
is the horse quest needed for the this secret area
No
A small edit should be made. You don’t actually have to finish chapter 5 for this quest. Just return to him after you beat the boss in the emerald hall and you’ll get the transformation.