Have you ever found a doorway with a simple lock in Hollow Knight: Silksong, and thought, “What could possibly be behind there?” Well, more than you could ever imagine, my friend, and a callback from Hollow Knight no less!
Once you pass through the doorway located in the Wormways, you’ll find a bug studying Lifeblood, or as he likes to call it, Plasmium. Thus, he will send you out on a quest to explore the cramped spaces of the Wormways and find him some samples. Do you enjoy hanging out with murderous flesh-eating worms? Lovely, then this is just the place for you.
If not, and you want to spend as little time here as possible, I’ll show you how to obtain the 3 Plasmium samples so you can return to the charming, more colourful side of Hollow Knight: Silksong.
Where To Find The Quest
First of all, you need to find a Simple Key. There are actually a few simple keys scattered around the world of Pharloom, but the easiest is found right at the start, sold by the vendor in Bone Bottom for 500 Rosary Beads.
In addition, you won’t be able to traverse this area without the Cling Grip, so grab that from Shellwood before you begin.
Next up, you’ll need to head to the entrance of the Wormways, which is located due west of Mosshome. You’ll have to make a jump across the gap where two large cages are hanging. Keep heading west through the area until you find a large door. Use your Simple Key and proceed.
Wend your way upwards through the area, and at the very top, through a vertical shaft, you’ll find Alchemist Zylotol and receive the Wish.
Finding the Plasmium Buds
Bud 1
Before you head down, equip the tool Zylotol gave you using the bench on the left. It counts as a red tool in your slots. It’s activated the same way that you might use a Sting Shard, for example.
The first bud can be found in the chamber below Zylotol, in the location marked in the image above. Watch out for the little worms that burst out of the ground and try to bite you. If you have the Crest of the Wanderer, you can quick-slash and keep these guys at bay before they reach you.
If you’re low on health, you can slash the worms that keep coming down from the ceiling. You can’t actually kill them, but you can regen off of them.
Bud 2
The next bud, is found way down, right at the base of the Wormways, where it starts to blend in with the Moss Grotto. Head down and to the east, and when the area starts looking green, you’ll know you’re in the right place. Head down a short corridor to find the next bud.
While you’re there, you might as well open up the shortcut right below the bud that leads back into the Moss Grotto.
Bud 3
The final bud can be found in the large chamber to the southwest. You can find this bud all the way to the left, just after the entrance to the westmost chamber. Suck up the final bud and then return to Alchemist Zylotol.
Quest Rewards
Once you return, he will congratulate you and give you a Plasmium Phial.
This phial is a red tool and can be used to give yourself an extra temporary mask of health. It has three uses, and it is recharged with the reserve upon sitting on a bench. In total, there are 20 uses. Once you’ve run out of phial charges, you can return to Alchemist Zylotol for a refill in exchange for rosary beads.
Hollow Knight: Silksong
- Released
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September 4, 2025
- Developer(s)
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Team Cherry
- Publisher(s)
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Team Cherry
- Engine
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Unity
- Franchise
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Hollow Knight
- Number of Players
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Single-player
- Steam Deck Compatibility
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Verified
