The Sunderpit

The old wagon-road towards Navarro had been sealed ages ago, with plenty of graphic warnings depicting dead animals, skulls, and the like. By contrast, the small spur road to the Academy research site was open and well travelled, though with several warning signs of its own, this time of falling rocks and debris. A local guardsman waved down Tarvo's power-wagon at the fork.
"Road's closed except for official business. Ah." The guard saw Tarvo's passenger. "My apologies, Ranger Vogel, but we have to make sure." He stepped back and waved them forward.
"Tougher security?" Tarvo twisted the hand lever to get the power-wagon moving again. "The stories about this place should keep most away."
Kyris shook her head. "The Academy's full of idiots. Couldn't get enough student volunteers to go out into the gas, so they placed an advertisement in the Monitor for people to come help them retrieve Sunder pieces with a per-piece payout. Now you have idiots coming here every season to try to make a red Florin or two, and a couple die gruesomely for their effort." The ranger watched the side of the road as the wagon rolled along the spur road. The forest here was doing poorly, the trees stunted and gnarled, but she supposed it was better that than the trees simply melting like they did farther in the Exclusion zone.
"I don't see how a single guard at the road stops anything, anyone can just wander through the forest and jump the fencing. I guess the gas would get them first." Tarvo frowned as they came up to the camp site. "Hold on, something's happening." 
The Academy research station was buzzing with activity, with a group clustered around one of the temporary huts in the center of the camp. They saw the power-wagon pull to a stop and waved at the riders excitedly.
"Hold that wagon! Don't bring it any closer!" The closest person was a woman, short and thin, but wearing heavy oilcloth protective gear and with a full breathing mask over her face. "Don't enter the camp until it's deemed safe!"
Tarvo cupped his hands to his mouth. "What happened?" 
The woman came closer to the wagon, but remained a stone's throw away, only close enough to speak without yelling. "A Sunder artifact boiled away the Ryssae oil we were using to contain it. Everyone who was in the tent it was in got sick, their skin is peeling off." The woman shook her head. "The Academician Grien has declared the camp in quarantine."
Kyris spoke up. "I'm under instructions from the Capital City to pick up some nobleman who was caught scavenging for Sunder illegally here. Are you aware of someone by the name of Pharyn Xander, seventh sun of Michael Xander?"
The woman made a noise under the mask that may have been laughter. "That's the fool that brought that piece back. He was holding it with his bare hands, if you could believe it." She shook her head. "He died screaming two days ago, his arm looked like it had been eaten by some kind of acid. We buried his body under a layer of oil ten feet deep in case whatever he had spread." 
She raised her arms. "Fat lot of good that did us. We've got six sick people and the rest of us are stuck in our tents preparing our own food. If I were you I'd turn around and go back to the Capital to request aid."
Kyris shook her head. "Unfortunately I can't return empty handed to the Capital. Would it be safe to transport the dead body in a oil bath inside a barrel?" She winced a bit at the thought of that barrel bouncing around the back of the wagon all the way to the Capital.
The masked woman shook her head again. "You'll have to talk to Grien for that. Maybe the body won't boil away oil the way the Sunder piece did." The woman folded her arms to think for a minute. "Go back to the fork in the road and let our guard know about this situation, and I'll get Grier out of his tent. My inkling is that he'll let you recover the body if you can make a quick run to town for some oilcloth and other materiel we'll need here."
Kyris nodded. "My thanks." Tarvo quickly turned the wagon around and rolled it back down the spur road.
He let out his breath in a deep sigh. "Felt like if I even breathed a bit I'd get that gas in me and start melting on the inside."
"You read too many of those tawdry journal pieces, Tarvo. The Sunderpit is well-studied." Kyris frowned. "Let's make sure we send Post to Alistair in the Capital, though. Whatever's happening here reminds me of that paper I read about Wizard Embers making mice sick. Maybe a wizard can come by and sort this out."
"You mean, like the time they all showed up and made this whole place worse?" Tarvo lay his head back. "No offense to our friend Alistair here..."

Manifestation

The Sunderpit is the result of an attempt to reclaim the lands of the Navarro Exclusion Zone for use by the Principality of Etoile. The death of the city was caused by some sort of alchemic reaction in the water table that produces continual outgassing, and it was theorized that, with the new aid of Magic, the site could be made safe for resettlement, and hardwood harvesting could be restarted. Teams from the Wizard's Association of Etoile and the Chemister's Pact were sent to a staging grounds near the site in order to conduct experiments, in the first season of 719.
At the start of the third season, the remediation teams had successfully excavated a large well just inside the exclusion zone perimeter, down to the water layer. While the wizards contained the noxious outgassing, the chemisters injected additional alchemic reagents into the well in order to test potential neutralizers. One such neutralizer was a mixture of Resonance Mineral, finely powdered, in an acid bath - the theory was the magic absorption power of Resonance Mineral could contain the reaction that led to outgassing.
While this mixture was successful in the experimental samples taken from the well, the post-disaster inquest determined that the researchers had failed to account for the latent magics that had been used regularly in the same area repeatedly for tens of weeks (for excavation and gas containment). Not long after the agent was injected, a localized earthquake shook the site, and the remediation teams were forced to evacuate the area quickly as their worksite collapsed into a massive sinkhole. Worse, the sinkhole itself was dumping noxious gases at an alarming rate, visibly covering the forest floor in a circular area roughly a half mile wide and melting all organic material it came in contact with, causing the trees in the area to liquefy.
Unlike the rest of the Exclusion zone, which is more or less geologically stable, with only gas-emitting cracks in the ground to indicate danger, the Sunderpit is an unstable and roiling landscape, with a perpetual toxic gas cloud flowing and receding from the well at its center (not unlike a tidal pool). Regular soil eruptions occur in the area at random, throwing piles of earth tens of feet into the air and releasing jets of lethal gas with no warning. The current accepted theory is that the resonance mineral is 'recasting' excavation spells, and some alchemic reaction in the soil is empowering the mineral to do this repeatedly; the Sunderpit has not noticably weakened in its severity or danger.
One positive aspect of this disaster is that, on the occasions that earth and soil is ejected out of the danger area, some samples of new and unrecognized materials are being recovered from the debris. These materials (named 'Sunders') have odd properties; a rock that was extracted had the ability to clarify cloudy water and render it drinkable, for example. The unstable magic of the area and the novel alchemic mixtures (as all of the alchemic reagants in the remediation camp fell into the pit on its creation) seem to be producing novel substances. This is of particular interest to The Academy of Etoile, which has set up a research camp at a safe distance from the Sunderpit for recovery and analysis of these materials, which vary from useful to exotic to extremely dangerous.

Localization

The Sunderpit should, by all principles of Progress, be recreatable safely - most of the reagents used in its creation are known to Etoile, and it was a man-made catastrophe in both the initial action during The War of Unification and the attempted cleanup. All attempts to recreate the phenomena at a smaller and safer scale have failed, and there is no desire to recreate it at-large and potentially destroy another few square miles of land. 
The Sunderpit remains the only active site of this phenomenon in Saibh, and attracts fortune-seekers and adventurers willing to brave the lethal gases and unpredictable earth in order to recover newly fused Sunder samples.

Type

Metaphysical, Arcane