Numismaton Gas

A blue-flamed volatile energy that burns harmlessly beneath the Hall of Fire’s stone platform, casting flickering azure light across the cavern walls. The Doctor identifies its residue on Timanov’s Trion circuit key, confirming its origin in Sarn’s destabilized energy matrix. It surges through pressurized conduits in the Seismic Control Centre, threatening catastrophic release if breached. The Master weaponizes it as a regenerative power source, hijacking Kamelion’s physiology to fuel his twisted revival scheme.

6 appearances

Appearances in the Narrative

When this object appears and how it's used

6 moments

S21E17 · Planet of Fire Part 3

Turlough and Peri sabotage the gas supply

The numismaton gas supply valve is targeted by Turlough for disabling through circuit manipulation. Its corroded brass surface and eroded Trion glyphs pose significant obstacles, requiring him to rely on fragmented memory and measured force. The valve’s operational status is uncertain given decades of disuse and the planet’s destabilized energy matrix, yet it remains the linchpin for interrupting the Master’s sacrificial fire.

Before: Mounted in the control bunker’s central dais, showing signs of corrosion, mineral condensation, and strain from decades of inactivity and inconsistent maintenance. The valve is intact but its responsiveness to reassembly or reoperation is unknown.

After: Unknown in the script excerpt—remaining status contingent on whether Turlough successfully cuts the gas flow during or after this exchange.

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S21E17 · Planet of Fire Part 3

Doctor uncovers forbidden Time Lord gas

Though not physically touched during this brief exchange, the numismaton gas supply system lurks conceptually behind the visible action. Turlough identifies it indirectly by the Doctor’s deduction, anchoring the residue’s significance to a larger infrastructure the Master controls to mass-accumulate the gas.

Before: Pressurized and cascading through unseen conduits beneath the cave, primed for catastrophic release.

After: No direct interaction changes its state or visibility, but its existence is now confirmed to the audience and Doctor.

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S21E18 · Planet of Fire Part 4

Triumvirate revealed by Misos Triangle

The numismaton gas burns in the Fire Cave’s blue flame, casting an eerie glow over the Hall of Fire. The Doctor identifies its residue on the Misos Triangle, confirming its Trion origin and reinforcing its role as a power source. The gas’s presence in the cave is both a calming influence (safe when controlled) and a looming threat (potentially deadly if unleashed).

Before: Burning harmlessly in the cave as part of the Sarn cult’s rituals.

After: Still burning, but now repurposed as a diagnostic tool and key to the escape plan.

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S21E18 · Planet of Fire Part 4

Doctor battles gas surge to save Sarns

The volatile numismaton gas within Sarn’s core is identified by the Doctor as having been triggered by the Master, surging dangerously toward the planet’s surface. Its imminent breach threatens to disable the planet’s inhibition circuits, turning a geothermal hazard into an instrument of weaponized destruction.

Before: Contained within the pressurized core, dormant but primed by the Master’s recent surge activation

After: Actively destabilized and expanding toward the surface with potential to breach containment

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S21E18 · Planet of Fire Part 4

Doctor humiliates miniaturized Master

The volatile numismaton gas is weaponized by the Master as the power source for Kamelion’s forced revival, coursing through reactivated organic-metal interfaces within the control box. Its presence turns the confrontation into a race against catastrophic energy release, with the Doctor’s analysis exposing how the gas amplifies both Kamelion’s torment and the Master’s delusional restoration plans.

Before: Pressurized and active, flowing through conduits toward Kamelion’s core systems to fuel the forced merger with the Master’s consciousness for the planned revival surge

After: Clearly identified and anatomized by the Doctor, its role in the Master’s scheme is publicly dismantled, leaving the gas surge temporarily stalled by the K-Master’s retreat order

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S21E18 · Planet of Fire Part 4

The Master reveals his final gambit

Numismaton gas is invoked by the Master as the imminent catalyst for his ‘supreme renewal,’ its volatile energy channelled through Kamelion’s form and Sarn’s fissures. The Doctor correlates its visual residue with Timanov’s key to validate the Master’s connection to the planet’s geothermal systems, marking it as the ticking clock behind the scene’s tension.

Before: Stable within pressurized conduits beneath the Hall of Fire, before surge activation

After: Still dormant but primed to surge in the next moment, linking to Sarn’s collapsing energy grid

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