The Alchemist’s Assistant is one of the more intriguing side quests in Hollow Knight: Silksong. Set deep within the Wormways, it introduces players to Alchemist Zylotol and his obsession with a strange substance called Plasmium. This guide walks you through how to unlock the quest, where to find all three Plasmium samples, and what rewards await once you finish your duties as the Alchemist’s reluctant helper.
How to Start the Alchemist’s Assistant Quest
To begin, you’ll need to unlock the Wormways, a maze-like section of Pharloom filled with hostile creatures and environmental hazards.
- Requirement – Simple Key
- You must first obtain a Simple Key, either by buying one from Pebb for 500 Rosaries or by defeating a strong enemy along Sinner’s Road.
- Requirement – Cling Grip
- The Wormways are built vertically, so you’ll need the Cling Grip ability from Shellwood to climb walls and reach Zylotol’s laboratory.
Once inside, climb to the upper Wormways and locate Alchemist Zylotol in his lab. He will ask Hornet to collect three samples of Plasmium for his experiments. Before you leave, sit at the nearby bench and equip the Needle Phial he provides. Without this tool, you cannot harvest Plasmium buds.
All Plasmium Locations
Plasmium looks like glowing blue flowers scattered throughout the Wormways. They are not marked on your map, so navigation can be tricky. Here’s where to find each one:
1. Upper Wormways – Beneath Zylotol’s Lab
The first Plasmium is close to where you start.
- Exit Zylotol’s chamber and drop down into the level below.
- Head left, climb above the spike pit, then drop again.
- Look for the blue glow in a nearby alcove.
- Hold the tool button to absorb the Plasmium with your Needle Phial.
2. Lower Wormways – Toward Moss Grotto
The second Plasmium lies deeper in the tunnels.
- From the first node, descend further into the Wormways.
- Stay to the right as you move downward.
- When the area turns mossy and green, you’ll spot the next glowing Plasmium bud tucked inside a side corridor.
3. Hidden Chamber – West of the Second Node
The final Plasmium is in a secret section.
- From the second bud, head left and climb past a spike pit.
- Use Wall Climb to scale the wall and jump across the next gap.
- Continue left until you find a breakable stone wall.
- Smash through and follow the path to the last Plasmium bud.
Optional Secret: Beyond this chamber, you can discover the remains of Zylotol’s previous assistant, overgrown with Plasmium. If you have the Needolin ability, you can interact with them to reveal hidden lore.
Rewards for Completing the Quest
After collecting all three Plasmium samples, return to Alchemist Zylotol. Your reward is the Plasmium Phial, a powerful tool that temporarily increases Hornet’s health.
Plasmium Phial – Key Details
- Grants three temporary masks when used.
- Comes with 20 reserve charges that automatically refill active uses at benches.
- Refilling reserves costs 50 Rosaries if you return to Zylotol.
- When paired with certain charms like Pollip Pouch, the health masks take on new effects, such as releasing a venom cloud when expiring.
This makes the Plasmium Phial an excellent survival tool, especially in tough boss fights or deep exploration runs.
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Quick Tips for the Quest
- Equip Needle Phial First: You cannot harvest Plasmium without it.
- Watch for Worm Enemies: Falling worms can easily disrupt your platforming, so time your movements carefully.
- Check for Shortcuts: While exploring for Plasmium, you can unlock paths that connect back to Moss Grotto and Bonegrave Path, making travel easier later.
- Save Beforehand: Since the Wormways are hazard-filled, sitting at Zylotol’s bench before starting ensures a safe respawn point.
The Alchemist’s Assistant Quest is more than just a fetch task—it’s a deep dive into the Wormways, packed with hidden lore and a valuable reward. The Plasmium Phial isn’t just another tool; it’s a lifeline that can make the difference in surviving Pharloom’s deadliest challenges. Whether you’re chasing completion or preparing for future boss fights, this quest is well worth your time. Play Now!
