Interplanar Threats

Gate Seventeen opened onto the Elemental Plane of Fire at 14:32 on a routine maintenance cycle. By 14:34, something that should not have been standing on the other side had crossed the threshold, killed two guards, and set the containment zone ablaze with heat that melted crystal-reinforced walls. The Planar Guard sealed the gate in twenty-eight seconds. The entity burned for another eleven minutes before a response team from Aelios neutralized it with a combination of cold-iron weaponry and targeted planar stabilization. Three dead. Nine injured. A formal review concluded that all protocols had been followed correctly. The entity had simply been faster than the protocols anticipated.

Gate Seventeen reopened two weeks later after structural repair and enhanced screening. Incidents of this nature occur roughly once per decade across the forty-seven active gates. They are rare enough to avoid public panic and frequent enough to keep the Planar Guard from ever relaxing.

Threat Classification System

Fleet Command and the Planar Guard jointly maintain a five-tier classification system for extraplanar and extrastellar threats. The tiers reflect response requirements, not raw power: a creature's strength matters less than what it takes to contain or eliminate it.

Class I: Territorial threats defend space instead of invading it. Rogue elementals near gate apertures, displaced fey creatures, and wildlife from connected planes that wander through open gates fall here. Standard guard patrols handle containment. Casualties are rare. Most incidents resolve through relocation instead of combat.

Class II: Hostile threats demonstrate active aggression. Organized raids from planar factions, predatory entities targeting gate traffic, and politically motivated incursions by extraplanar groups require coordinated military response. The Planar Guard escalates to Fleet support when Class II threats exceed local capacity.

Class III: Catastrophic threats endanger entire installations or population centers. Major elemental breaches, large-scale fey incursions, and Shadowfell infection events fall here. Planetary defense systems activate. Civilian evacuation protocols engage. The last Class III event occurred eighty years ago.

Class IV: Existential (Localized) threats could destroy a world or major installation if unchecked. The Abyssal Incident of 180 years ago is the sole confirmed Class IV event in Trisurus history. Full Fleet mobilization is authorized. The Consortium Council assumes direct oversight.

Class V: Existential (Systemic) threats endanger the entire Trisurus system or the crystal sphere itself. The Gyre is classified as a standing Class V threat, the only permanent entry in the category. No containment protocol exists. Response doctrine consists of study, preparation, and the uncomfortable acknowledgment that Class V threats may exceed Trisurus's capacity to address.

Elemental Threats

The twenty-three gates connecting to the Elemental Planes provide essential resources: fire for energy, earth for raw materials, water for purification systems, and air for atmospheric processors on space installations. The planes also produce threats proportional to the energy being extracted.

Rogue elementals cross through gates with some regularity. Most are territorial responses to extraction operations, and the Planar Guard has refined containment to routine efficiency over millennia. Standard procedure involves planar anchoring to prevent the elemental from drawing additional power, followed by forced displacement back through the gate.

The Aelios Forge Breach, four hundred years ago, demonstrated what happens when routine fails. An industrial-scale extraction portal on Aelios destabilized during a resonance cascade, and a fire elemental of unprecedented size crossed through before containment could engage. It consumed three city blocks of industrial infrastructure and required the combined effort of two Fleet warships and a ground assault team to bring down. Forty-one people died. The incident prompted a complete overhaul of extraction safety protocols and the installation of redundant stabilization arrays at every elemental gate.

Fey Incursions

Six gates open to the Feywild. Diplomatic relations with the archfey courts are formally cordial and practically unpredictable. The fey operate on logic that resists Trisuran analysis: alliances shift on aesthetic whim, grudges span centuries without obvious cause, and agreements that appear straightforward contain implications that surface decades later.

The Wild Hunt has crossed into Trisurus space three times in recorded history, pursuing quarry that had fled through the gates. Each incursion was brief, targeted, and spectacularly destructive to anything between the Hunt and its prey. Diplomatic protests afterward produced apologies that may or may not have been sincere. The Planar Guard now maintains Hunt-specific detection protocols, though their reliability against fey concealment magic is uncertain.

Travelers returning from the Feywild occasionally discover that temporal displacement has occurred. A week spent beyond the gate may correspond to a year in Trisurus, or a year may compress to minutes. The Temporal Institute monitors returning travelers for temporal anomalies, and the Feywild gates carry posted warnings about duration uncertainty.

Transformation is the subtler danger. Citizens who spend extended periods in the Feywild sometimes return altered in ways that resist reversal. Changed temperaments, shifted priorities, physical modifications that no treatment can undo. Whether these transformations are harmful or merely different is a question that divides ethicists and entertains the archfey enormously.

The Shadow Plague and the Shadowfell

Four gates connect to the Shadowfell, and every one of them is monitored with a vigilance that borders on paranoia. The reason has a name: the Shadow Plague.

Shadow-stuff that leaches through gate apertures can infect living tissue, producing a progressive condition that begins with emotional flattening, advances to sensory dulling, and terminates in full personality dissolution. The infected individual does not die. They become something else: aware, ambulatory, and emptied of everything that once made them who they were. Early-stage infection responds to treatment. Late-stage cases are irreversible.

The Nightwalker Incident, three hundred years ago, escalated beyond infection. A Nightwalker, a towering undead entity of compressed negative energy, breached Gate Thirty-One during a maintenance window and reached the outskirts of an Aelios research district before Fleet response teams brought it down. Seventy-two casualties. The battle lasted nine minutes. Post-incident analysis revealed that the Nightwalker had been drawn by the concentration of living souls near the gate, attracted like a predator to prey.

All Shadowfell gate personnel now undergo mandatory psychological screening every thirty days. Rotation cycles are capped at six months. Returning travelers submit to medical evaluation that includes soul-integrity scanning. The precautions are extensive. The alternative is worse.

The Abyssal Incident

One hundred and eighty years ago, Gate Forty-Two opened onto the Abyss for diplomatic contact with a faction that had expressed interest in trade negotiations. The faction's representative was a balor named Vorthekk the Unbound. Negotiations lasted four hours before Vorthekk revealed that "trade" was a pretext and the true purpose of the contact was military reconnaissance.

What followed was the only confirmed Class IV event in Trisurus history. Vorthekk's forces, a strike team of demons concealed within his diplomatic entourage, overwhelmed the gate's guard contingent in minutes. The breach expanded as Vorthekk used the gate's own infrastructure to widen the aperture, allowing larger forces through. Fleet response arrived within twenty minutes. The battle to reseal the gate lasted six hours. One hundred and twelve Trisurans died. Vorthekk was driven back into the Abyss, though confirmation of his destruction was never obtained.

The aftermath produced Trisurus's most divisive infrastructure debate: whether to close the Abyssal gates permanently. Proponents argued that the Abyss offered nothing worth the risk. Opponents countered that sealing gates did not eliminate the threat, merely blinded Trisurus to it, and that intelligence gathered through controlled access was preferable to ignorance. The gates remain open. Security was tripled. The debate continues.

Wildspace Predators

Beyond the crystal sphere's boundary, the Astral Sea and wildspace harbor threats that no gate classification covers. The Fleet encounters these during patrol and exploration missions, and the contact reports read like a bestiary of nightmares.

Astral predators hunt in the spaces between crystal spheres. Most are solitary, territorial, and avoidable with competent navigation. Void krakens, the largest confirmed predators, have tentacle spans exceeding a thousand feet and can disable a spelljammer by wrapping its hull and crushing the shield arrays. Fleet doctrine prescribes evasion over engagement. Three ships have been lost to void kraken attacks in the past millennium.

Hollow Ships are a different kind of threat. Dead vessels from collapsed spheres drift through wildspace, their crews gone, their systems dark. Some are genuinely empty. Others carry automated defense systems that activate when living beings approach, or contain preservation wards that have kept their original occupants in stasis for centuries, not always in a condition that resembles sanity. Salvage teams operate under strict protocols: approach with shields raised, scan before boarding, and never assume a Hollow Ship is truly abandoned.

Drift Hunters are entities native to the Astral Sea itself, predators that track the magical signatures of spelljammer helms across vast distances. They appear as distortions in the astral medium, visible only to experienced navigators or sensor systems calibrated to detect their specific resonance pattern. A Drift Hunter latches onto a ship's hull and slowly drains its helm power over days or weeks. Ships that lose power in the Astral Sea drift until rescue arrives or doesn't.

Gyre Entities

The Gyre resists classification. The cosmic maelstrom at the edge of known space produces phenomena that existing threat frameworks cannot categorize, and ships that venture too close report encounters that defy conventional description.

Reality storms sweep outward from the Gyre's periphery, zones where physical laws become unreliable. Objects change mass. Light bends in directions that geometry does not support. Time stutters, repeats, or runs in directions that the Temporal Institute refuses to call "backward" because the word implies a linearity that does not apply. Ships caught in reality storms sustain damage that repair crews struggle to reverse because the damage does not always follow consistent rules.

Temporal predators have been reported by three separate Fleet vessels, though the reports contradict each other in ways that may reflect the nature of the entities rather than observer error. Something hunts near the Gyre's edge. It operates in temporal dimensions that organic minds perceive imperfectly. What the crews described may have been a single entity, many entities, or the same encounter experienced from different points in a timeline that does not proceed in one direction.

Ships that do not return from Gyre proximity are classified as "lost to navigational hazard." The classification is accurate. It is not complete.

Far Realm Incursions

Two thousand years ago, a team of Trisuran researchers attempted to open a gate to the Far Realm, the space beyond all known planes of existence. The gate functioned for eleven seconds. What came through in those eleven seconds was not an entity in any conventional sense. It was a geometric anomaly, a spatial configuration that organic minds interpreted as architecture but that did not correspond to three-dimensional reality. The research team sealed the gate, quarantined the site, and spent the next decade studying the residual effects.

The anomaly they sealed is called the Geometry. It occupies a containment facility on Aelios, stabilized by a permanent array of defensive fields and monitored by a rotating staff who serve six-month assignments with mandatory psychological evaluation before, during, and after. The Geometry does not move. It does not grow. It does not interact with its containment. It simply exists in a way that the surrounding universe finds uncomfortable. Instruments near it produce readings that are internally consistent but incompatible with readings taken from identical instruments ten meters away. People who spend extended time near it report dreams of spaces that have too many corners.

No further Far Realm gate attempts have been authorized. The standing prohibition is the only item on the Index of Proscribed Research that has never generated a formal petition for reconsideration.