Overview
Forbidden Knowledge is the third and final quest in Chapter 4: The Price of Knowledge. It follows the Daily Life quest and leads directly into Chapter 5: Guest Unbidden. This is one of the longest quests in the game, combining investigation, puzzle-solving, a boss fight, and platforming through the Abyss.
Chapter Context
Kliff receives a cryptic letter from Alustin, directing him to the Scholastone Institute to uncover secrets related to the Abyss. The quest delves into the nature of Abyss Artifacts and the dangers of experimenting with forbidden power, setting up the major revelations in later chapters.
Objectives
The Words of Alustin
Travel to Hernand and locate the beggar sitting near a wall in the orange-marked area.
Give a coin to the beggar to receive Alustin's Letter.
Read the letter in your inventory.
Scholastone Preparation
Find the Fence building to the left of the Message Board in the Hernand plaza.
Speak with Darroch to obtain the Scholastone Uniform.
Travel southwest to the hidden cave entrance blocked by a magical barrier.
Equip the Scholastone Uniform. The barrier lifts, granting passage.
Use Focus Force Palm on glowing green energy nodes along the path to unlock the route forward.
Meet Dean Grundir
Arrive at the Scholastone Institute and meet Dean Grundir on the bridge.
Attend a meeting with Octavius.
Wait 24 in-game hours before the next segment becomes available. You can rest or explore during this time.
Gate to the Otherworld
Return to Octavius to begin the underground experiment.
Solve the lock device puzzle by pressing the squares in this order: Top Left, Middle, Top Middle, Bottom Right, Bottom Left, Middle Right, Bottom Middle, Middle Left, Top Right.
Use Axiom Force to grab battery cubes and Force Palm to insert them into the pillar sockets.
Pull out the unstable core using Axiom Force.
Defeat the Tenebrum boss (see boss strategy below).
Spire of the Stars
Travel northeast from the main building following the staircase path.
Insert the corrupted core into the center of the sealed door.
Retrieve three power cores from diamond-shaped holders using Force Palm.
Place the cores into the correct slots: first shape at the top position, second at the second notch, third at the bottom, fourth at the third notch.
Ride the elevator to the top floor and enter the Abyss Gate.
Obsession and Madness
Step on the first Abyss Nexus to unlock fast travel within this area.
Use Axiom Force on the conductor slot embedded in the large pillar.
Navigate the aerial-view platform puzzle: use L2/R2 (PlayStation) or LT/RT (Xbox) to select pillars, and X/A to raise them. Activate the central pillar first, then work outward.
Climb the walls to reach the upper level.
Use Force Palm on the illuminated pressure platform to complete this section.
Casted Shadow
After the cutscene, return to the Scholastone Institute.
Speak with Dean Grundir.
Return to the Howling Hill camp and enter your tent to complete the quest.
Boss Fight: Tenebrum
Tenebrum is a flying enemy encountered during the Gate to the Otherworld segment. Standard ground attacks cannot reach it. To deal damage:
Climb one of the pillars in the arena.
Jump toward Tenebrum from the pillar's peak.
Use Force Palm attacks mid-air to strike it. Three to four direct hits will bring it down.
Use the triple Force Palm technique: execute Force Palm three times consecutively mid-air to catapult upward and close the distance, then glide to the next pillar to repeat.
Rewards
Scholastone Uniform x1
Abyss Artifact x1
Honey Tea x10
Tips
The 24-hour wait after meeting Dean Grundir is a good opportunity to tackle side quests or gather materials.
For the lock device puzzle, write down the button sequence or follow it carefully: Top Left, Middle, Top Middle, Bottom Right, Bottom Left, Middle Right, Bottom Middle, Middle Left, Top Right.
During the Tenebrum fight, patience is key. Climb, jump, strike, and glide to the next pillar. Do not try to rush it from the ground.
In the Abyss platforming section, activate the central pillar first during the aerial puzzle. This creates a stable path to reach the outer pillars.
Keep the Scholastone Uniform in your inventory after the quest. It may be useful for accessing restricted areas later in the game.
Completion
A document opposing the victim's research and numerous signatures were found. Testimony stated that the murder weapon was not of Delesyian style and that someone headed upstairs immediately after the incident. The critical clue was the fact that a scholar named Corvin frequently visited the area around the well.