Silksong Tools & Guides
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Plasmium Phial – Hollow Knight: Silksong Red Tool

HEALTH INJECTION & OVERDOSAGE REGENERATION

A Red Tool that injects Plasmium to temporarily grant extra masks (up to +5, turning them blue for passive regeneration at 1 mask every 6 seconds). Complete the Alchemist's Assistant quest in Wormways to obtain this powerful health tool.

Plasmium Phial red tool icon from Hollow Knight Silksong showing health injection vial design
ACT 1
WORMWAYS (Alchemist's Assistant)
HEALTH
REGEN
QUEST
1
SLOTS
3–5
MASKS

IMPACT STATS

DAMAGE
0%
SURVIVAL
95%
MOBILITY
10%
UTILITY
80%
ECONOMY
30%

ACQUISITION (ALCHEMIST'S ASSISTANT)

Method:Quest completion
NPC:Zylotol (Alchemist's Assistant)
Location:Wormways
Requires:Needle Phial + 3 Plasmium samples

Find Zylotol in Wormways, collect 3 Plasmium samples from buds using the Needle Phial, then return to claim your reward.

DESCRIPTION

Injects Plasmium to temporarily grant +3 to +5 extra masks, turning them blue for passive regeneration (1 mask every 6 seconds). At 9+ masks, overdosage replaces your base health with regenerating blue masks—Bind heals only 1 mask (or 2 with Multibinder), but you gain continuous health regeneration.

Overdosage builds: 9+ masks for near-invincible regeneration
Early Act 1 availability via Alchemist's Assistant quest
Pairs well: Architect Crest for infinite refills and Multibinder for enhanced Bind healing

RECOMMENDED BOSSES

Last Judge

Overdosage builds excel against this brutal Act 3 boss with ball and chain attacks

First Sinner

Blue mask regeneration helps survive area attacks and environmental hazards

Savage Beastfly

Extra health buffer for learning patterns; overdosage makes add management trivial

ADD TO BUILD PLANNER

Add Plasmium Phial to Build

Plan your perfect health regeneration build with Plasmium Phial

HEALTH & SURVIVAL TOOLS COMPARISON

ToolSlotsActSurvivalUtilityEconomyNotes
Plasmium Phial115/54/52/5Blue mask regen; overdosage at 9+ masks
Multibinder224/53/53/54-mask Bind heal; pairs with Plasmium Phial
Reserve Bind133/54/54/5Free Bind healing; Act 3 quest reward

FREQUENTLY ASKED QUESTIONS

A: Plasmium Phial takes 1 Red slot, making it easy to fit in early pouches alongside other health-focused tools.

A: Complete quest by collecting 3 Plasmium samples from buds in Wormways using the Needle Phial tool, then return to Zylotol for the reward.

A: At 9+ masks, your base health is replaced with regenerating blue masks. Bind heals only 1 mask (or 2 with Multibinder), but you get passive regeneration every 6 seconds.

A: This is a known bug. Ensure you have enough Shell Shards (13 per refill), complete Advanced Alchemy for Plasmium Gland, or try reloading your save.

A: Combine with Architect Crest for infinite refills, and aim for 9+ masks to trigger the overdosage regeneration effect for near-invincible builds.

A: Complete Advanced Alchemy by defeating 10 Plasmified enemies. This unlocks infinite refills at benches for 13 Shell Shards each, with a 20 reserve limit.