The Rattle-Drum Questline is a hidden side quest in Chapter 2 of Black Myth Wukong, and it involves using a certain Old Rattle-Drum Key Item to communicate with the spirit of a child, and unlock the a hidden boss - the Mad Tiger.
Where is the Old Rattle-Drum Found
This secret questline starts when you get the Old-Rattle Drum Key Item. It will drop from a Yaoguai Chief Miniboss called Tiger's Acolyte. This battle is located at the far end of the Yellow Wind Formation region, at the very end of Windrest Hamlet along the large stone bridge that leads back to the Fright Cliff region.
After defeating the Tiger's Acolyte, you get the Old-Rattle Drum, which seems to belong to the Acolyte's son, but no other details are given. You need to find three places where you can use the drum to summon a spirit, in different locations throughout Yellow Wind Ridge. The only clue you have is that when you enter the right place your vision will warp, and you will hear a child's voice calling out to you.
First Location - Windrest Hamlet
The first place you can use the Old-Rattle Drum is near where you fought the Tiger's Acolyte, back in Windrest Hamlet. You'll go back across the bridge to the Windrest Hamlet Shrine and pass back through the large gate, and you'll immediately turn left to the large house surrounded by seated Withering Corpses.
A visual cue will appear with a child's voice calling you, and you can use the Rattle-Drum in front of the house. Be careful, as doing this will prompt all nearby corpses to attack you, but you'll also get some interesting dialogue from the kid.
Second Location - Windseal Gate
The second location where you can use the Old-Rattle Drum is on the way down from the sealed stone door where you fought the King of Flowing Sands and his son the Second Rat Prince, using the items Keenness of Tiger and Sterness of Stone from the Vanguard bosses (The Stone Vanguard and Tiger Vanguard) to open the door.
From the door, head down to a bridge, but turn right to pass a dilapidated building where some Weasel Captains are hiding.
Beyond the ruined building, there was a long, roof-like passageway and several Withering Corpses wandering around, along with a Ginsengling hiding next to a wooden chest. If you've used the Old Rattle-Drum in Windrest Hamlet, you'll hear the spirit of a child calling you again. Use the drum here, and get ready to face the zombies while he's talking. Surprisingly, he mentions a secret and a well before he stops, giving you the last clue for the third location.
Third Location - Sandgate Village
Many small wells are located around the Yellow Sand Ridge area, but the one you are looking for is located in Sandgate Village. Return to the area where you fought the Earth Wolf and rescue the Horse Guai tied to the large statue.
Look to the left of the statue's altar, and you'll see a small rice field in the back with lots of skeletons, and a well. Use the Rattle-Drum here one last time and the child's spirit will appear before you, inviting you to jump down the well to meet a "friend."
Unfortunately, if the muffled, humming noises from below are any indication, you probably won't meet a pretty face there. You can interact with the well to descend into a secret area, where you will face a very difficult and dangerous secret boss, the Mad Tiger.
Yaoguai Chief Battle - Mad Tiger
The removed brother of Tiger Vanguard, Mad Tiger may not have a sword, but he is a violent and powerful boss that is more dangerous and possibly more difficult than the two Tiger bosses. Because of this, you'll want to equip yourself with the best gear in Chapter 2 — you may also want to finish the chapter and come back from Chapter 3 if you can't handle this boss. Make sure you have enough potions to increase your damage output and damage reduction.
The Mad Tiger fight starts with a quick jump, coming down with a slashing blow that you have to dodge and then counter.
There are also times when he will do a feinting strike by jumping to one side of you with an uppercut, and then change direction to knock you down after a slight delay in your direction.
There is also another jumping attack that he can do to spin his body high in the air like his brother before falling, only this attack causes his head to hit the ground. This can be favorable to you with proper avoidance, as he slowly gets up while holding his head from the impact.
Although he does not have a sword, Mad Tiger's fists are sufficient, and can be used in many combo attacks. His most common attack starts with an uppercut punch, followed by a downward strike after a short pause, and followed by a large sweeping claw swipe that spins him around. If you want to try using Rock Solid, build it up for the swipe so he doesn't attack on his first two moves.
Annoyingly, he can also launch a similar strike with only the first two hits, but at a faster speed.
He also has another combo strike that often starts with a downward punch, followed by two large horizontal claw swipes that spin his body, and ends with him pulling his fist off the ground with a rising swipe while jumping backwards with momentum. Immobilize him before he escapes if you want to retaliate.
Many of his attacks can transition into two quick claw swipes with each hand where his arms remain on either side of his body, and after a moment, he will suddenly swing violently with both arms. and an outward cross slash that you can try to Immobilize to prevent. Rock Solid can also help, but it probably won't weaken him enough to stop the move.
Be careful, as he will often follow up a two arm slash by jumping straight up into the air before coming down with a slamming attack.
After you've fought him a few times, you can hear him screech in anger, which will give a quick indication that he'll release a very loud noise that can deal damage to you if you're close to him, and will also knock down stone from the ceiling at you, and you'll need to think fast to avoid it.
In this enraged state, he will unleash more jumping attacks, such as a foot-first jump that ends in a slam with his right arm, before spinning upwards in another rising claw swipe as he sends his yourself in the air, and come down on you again for a huge slam that shatters the ground around the point of impact.
Another very dangerous combo he can do after a shout seems to last a lot, so this is a perfect opportunity to try to Immobilize him or use a Transformation Spell if you're in danger of dying from his attacks . He'll spin around you before jumping up close with a claw strike, followed by a delayed upward slash, and a second after that, before raising his arm for a moment and then slashing down twice in quick succession, and a final delayed two-handed slam! Make sure you have enough stamina to keep dodging continuously for this long combo attack.
Another variant after his scream that you rarely see — usually when you're at some distance from him, he'll do a longer terrifying scream, and then release a projectile from his mouth at you with almost no warning!
There are times after performing slam attacks that he may keep his claws buried in the ground. If he keeps crouching while gathering strength, it means he'll pull out his fists to unleash a shower of rocks your way.
There are other times when he'll pick up a boulder, but instead of throwing it, he'll jump across the room to personally deliver the boulder into your face, which can cause massive damage.
And if the screams of rage and subsequent dangerous attacks weren't enough, Mad Tiger also has a secret acquisition. This often seems to happen in response to being staggered, causing him to drop to his knees with one hand on the ground. As he stands up, he will do this by quickly jumping towards you, landing with a quick uppercut.
If you can't dodge as he falls, he'll throw you into the air, pick you up, and slam you into the ground repeatedly — which usually results in instant death if you don't have full health.
Expect this fight to take a lot of practice, and major upgrades to your skills to deal enough damage to survive the fight. While most Rock Solid deflections aren't enough to stop him, retaliating with charged heavy strikes or crashing into an Immobilize can sometimes stagger him a few times and give you a lot of openings. Using Azure Dust Transformation is also useful to absorb his most damaging combos and counter heavy hits to drain his health.
Keep practicing against dodging his moves, finding the right times to deflect the end of his combos (or just use Cloud Step to dodge) and always keep a close eye when you stagger him to avoid his rising grab. Having a concoction to increase your maximum health can be useful if you can't avoid his grab or long combo.
When Mad Tiger finally falls in front of you, he will release his Mad Tiger Spirit for you to absorb, and drop Blood of the Iron Bull, Yaoguai Core, Stone Spirit, and 1,023 Will. Make sure to search the bottom of the well carefully too, and you'll find a large wooden chest containing a Plaguebane Gourd!