The kingdom of Pharloom brims with secrets, and among its winding tunnels lies one of Hollow Knight: Silksong’s more intriguing side quests: Alchemist’s Assistant. This quest, given by the mysterious Alchemist Zylotol in the Wormways, invites Hornet to take on the role of an apprentice in pursuit of rare materials. Though the task may seem simple—gathering Plasmium and later Plasmified Blood—the dangers of the Wormways ensure that this errand feels like anything but routine.

Whether you’re hunting down glowing buds or fending off hostile creatures, this guide will walk you step by step through completing the Alchemist’s Assistant quest in Silksong, including all Plasmium locations, how to use the Needle Phial, and what rewards await you.

How to Start the Alchemist’s Assistant Quest

The journey begins in the Wormways, a perilous subterranean region accessible after leaving Shellwood. If you have a Simple Key, you can also venture deeper through locked passages. Expect hazards everywhere: giant worms erupt from walls, ceilings tremble with lurking predators, and the labyrinthine layout makes navigation a trial of its own.

The character Hornet is shown sitting on a bench in a dimly lit, blue-hued laboratory next to the alchemist character in the video game Hollow Knight: Silksong. — Credit: Team Cherry

At the upper reaches of the Wormways, tucked away in a secluded laboratory, you’ll find Alchemist Zylotol. Speak to him, and he will lament the failures of his previous assistant before offering Hornet the position. Accept, and you’ll receive the Needle Phial, a special tool essential for the quest. Rest at the nearby bench to equip it before proceeding further.

Plasmium Locations in the Wormways

Your first task is to harvest three Plasmium Buds, glowing nodes that pulse with a bright blue light. Each requires the Needle Phial to extract their essence. Approach a bud, hold the extraction button until fully charged, then release to gather the Plasmium.

Here are the three locations you need to visit:

Plasmium Bud #1 – Below Zylotol’s Quarters
From the Alchemist’s workshop, drop straight down. In a chamber directly beneath, you’ll find the first bud glowing in the shadows.
Plasmium Bud #2 – Toward Bonegrave Exit
Continue descending into the Wormways and head toward the corridor that links back to Bonegrave. The second Plasmium source sits near this exit, faint but unmistakable in its glow.
Plasmium Bud #3 – Lower Left Chamber (Memory Locket nearby)
Travel to the far bottom-left section of the Wormways. The chamber resembles a maw lined with jagged stone “teeth.” Deep within lies the third bud, close to a collectible Memory Locket.

Once you’ve secured all three, return to Zylotol to complete this stage of the quest.

A vibrant, stylized digital painting of the Hollow Knight: Silksong protagonist, Hornet, preparing to fight the Plasmified Zango boss.

Advanced Alchemy: Collecting Plasmified Blood

Zylotol’s ambitions do not end with Plasmium. After turning in the first objective, he entrusts Hornet with Advanced Alchemy—a continuation of the quest that requires gathering 10 Plasmified Blood samples.

Here’s what you need to know:

Needle Phial in Combat: Unlike Plasmium Buds, Plasmified Blood must be drawn from living enemies. Use the Needle Phial mid-fight, timing your extractions between dodges and attacks.
Best Targets: Smaller worms known as Plasmids are the easiest prey. Larger ceiling-dwellers like Plasmidas are more dangerous and often out of reach.
Boss Encounter – Plasmified Zango: A breakable wall near the third Plasmium node hides a chamber where you’ll face Plasmified Zango, Zylotol’s unfortunate former assistant. Though sluggish at first, his speed increases as his health drops. Successfully extracting from him yields multiple samples of Plasmified Blood.

A close-up of a game menu from Hollow Knight: Silksong asking "Give Items?" with icons for "Plasmium" and "Needle Phial" visible, showing the character Hornet interacting with the alchemist. — Credit: Team Cherry

Rewards from Alchemist Zylotol

Completing Zylotol’s experiments rewards Hornet with powerful tools that can shift the balance of survival in Pharloom:

Plasmium Phial (Quest Reward – Alchemist’s Assistant)
A red-type tool that grants Hornet a temporary health pip, lasting around five seconds. Perfect for clutch moments in boss fights.
Plasmium Gland (Quest Reward – Advanced Alchemy)
A permanent upgrade that automatically replenishes your Plasmium Phial charges whenever you rest at a bench, ensuring you always enter battle prepared.

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