You play as Kris in the retro RPG adventure,Deltarune. Together with Ralsei and Susie, you need to work your way to the Dark Fountain to seal it. On your journey, you’ll meet different characters, face several enemies, and take on various challenges.

Much like the previous chapters of Deltarune, there are secrets that can be uncovered when you succeed in certain challenges. Oftentimes, these secrets are optional but will reward you with a powerful item. One secret in chapter four is an optional boss that you can fight to receive a special weapon for Susie. Finding this boss starts with a golden piano puzzle.

How To Find The First Part Of The Golden Piano Piece

To begin this puzzle, you first need toobtain a toolthat will allow you toscale certain wallsin the area. The journey to getting this tool starts with the room locatednortheast of Old Man Gerson’s study. After you receive the tool,head back to the starting roomandclimb the wallall the way to the top. You’ll seea golden pianoat the very top. You’ll need to return here after you getthree parts of a piece.

To the left of the piano isa note with cluesas to where you canfind each part.

For the first piece,head to the room with a fountainwhere you canmake a donation. Donating to the fountain will split it for a moment,revealing a door behind it. Go through this door and you’llenter a darkened room. Go through the room andlook for a yellow ripple. Approach it, and you’ll be notified thatit is a wall made of bells.

Make your way up the walland keep moving along the path ahead. You’ll seeyellow buttons on the groundthat will light up the path witha yellow ripplingwhen stepped on. Use them tofind the path forward. Keep going until you seea blue button. Pressing it willreveal a part of the piece.

Anenemy emitting a red ripplewill then appear and willstart to chase you. Quickly exitalong the same pathyou took.

How To Find The Second Part Of The Golden Piano Piece

To get thesecond part of the piece, you need to head back to the doorby the bookcases and the stoolwhere you helped Old Man Gersonreach for a green book.Go westtowards the darkened area withmoving shadow monstersand blue buttons. In the northwest section of this area isa wall which you can climb. Make your way up toget to the next area.

The next area will havea wall you can scale, butwater will be fallingfrom certain parts. Make your way to the top whileavoiding the flowing water. There will bea container filled with waterat the top.Interact with itand when you turn to leave, you’ll beconfronted by a water cooler. Complete the battle that ensues, and you’ll be rewarded withanother part of a pieceafterward.

How To Find The Third Part Of The Golden Piano Piece

For thelast part of the piece, return to the door withthe bookshelves and the stool. This time,go east. Right past thedark hallway with tall windows, you’ll reach another area witha climbable wall. Scale this wall toreach a platform with a door.

Past the door isanother dark areasimilar to theroom behind the fountain. Make your way through the different obstaclestowards a figure on the east sideemitting awhite ripple. It will direct you tohead up northwherea short hallwaycan be found. At the end of the hallway isa yellow buttonthat will revealthe last part of the piecewhen stepped on.

Return to the golden pianoonce you have all the parts of the piece. When youplay the piece, you’ll find that there isa room behind the fireplaceback in Old Man Gerson’s study.Return hereto finda special itemand meeta secret boss.

How To Beat The Secret Boss

When you enter the roombehind the fireplace, you’ll finda powerful axesitting on a stone surface. This isthe Justice Axewhich can be given to Susie for an additional12 points to her attack. To obtain it, you will need tobeat the secret bosswhich turns out to beOld Man Gerson.

The fight against him is challenging becauseSusie will have to fight him aloneand you will beunable to use itemsduring the battle. You’ll also need to rely on bothyour dodging and blocking skillsfor his different attacks. During the battle, your soul will turneither green or red. When it’s green, you’ll beunable to moveand will have toblock incoming attackswith your axe.

In general, this boss fight isa battle of endurance. You need tokeep your health upuntil the end ofOld Man Gerson’s long speechand Susie comes to a realization.

Green Soul Attacks

Whileyour soul is green, you’ll only be able to move your axe toblock incoming attacksfrom multiple directions. At first, your soul will beencased in a boxand you will only have to block attacks coming from thetop, bottom, and sides. As the battle wears on, the box willturn into a hexagonand you will need to block attackscoming from six sides.

When he attacks with arrows, you need topay attention to their speed.

Some will come at youslower than others. When this happens,block the fast arrowsbefore turning your attention to the slow ones.

Another move involveshurling turtle shellsat you. Pay attention totheir different colors. Their color will indicatehow many more timesyou need to block them for them tobe destroyed. Only when theyturn yellowwill they take onlyone more block to break.

Red Soul Attacks

Whileyour soul is red, you will be able tomove around. You can use this time totry and gain TPfromclosely dodgingOld Man Gerson’s different attacks. That said, don’t attempt to do so if you end uptaking too much damage.

In one attack, he will whacka large green shellat you, making itbounce in different directions. You need to dodge boththe shell and the star trailit leaves behind. At the end of this attack, he’ll whack the shell fromdirectly above youand it willburst into a confetti of small starsthat you need to dodge.

Another attack will have himthrow dozens of tiny axesat you for a short period, after which he’ll startthrowing larger axesbefore finishing off the attack withone giant axe.

The last attack is one where he swings at you withhis Hammer of Justice. The attack zones willshine whitebefore he strikes, giving you the opportunity to move away safely.

Susie’s Actions

During the fight, Susie’s attacks will miss but willgrant you more TPcompared to defending. You will need TP because Susie’s two available actions will be your lifeline for the fight. Youronly source of healingwill beSusie’s Ok Healwhich costs83 TP. Rude Buster costs50 TP, but using it willshorten the fight.

When you use Rude Buster, Old Man Gerson willdeflect itand hurl it back at you. You’ll need tohit it backtowards him. Every time you use this move, he’ll deflect itan additional timefrom the last.

When you win the battle, you’ll be rewarded withthe Justice Axeanda Shadow Crystal.