From Hammered Gold and Gold Enamelling

At the top of the staircase down to Petrus’ laboratory lounged a large golden housecat, idly extending and retracting bladed steel claws. Its chest held an Earth Motive Stone.

“Why gold?” Hadrian asked.

“A thin layer of gilding, to prevent tarnishing on a bronze body. Partly for shock and awe, and partly because any impurity not of metal, even from the air, bears some potential to detract from the Motive Stone’s ability to exert motive force on the body. At least, where an Earth Stone is used. I haven’t found the time to build a bird without the gilding and test it against one with.”

He pushed open an iron-plated door. The room beyond had walls of human brickwork, but a smooth, seamless floor that suggested it had been built on the foundations of a destroyed Nephilic structure, or perhaps above the ceiling of an intact subterranean one. The far wall looked out on the sea through iron bars, and two figures waited inside: an engraver at a table, putting the finishing cosmetic touches on a bronze spider; and a northman palace guard standing in front of a safe in the room’s center, a little more than man-high and twice as wide, with all its surfaces plated in copper and a shallow, round socket where one might expect a keyhole, or some other means of actuating the lock.

“This is what I wanted to show you.” The guard stepped aside as Petrus approached the safe’s door. From a pocket somewhere between his layers of robe, dalmatic, and multiple tunics, he produced a black Water Motive Stone set in a a claw-like, iron-handled fixture, not unlike a short fire-poker. He held the stone to the socket, with the handle angled straight upward, and slowly rotated it a quarter-turn. A rushing sound, like water in pipes, echoed inside the door, and it swung open.

The inside of the safe, too, was lined with copper, and had copper shelves along the walls. Though there were bits of metal or carved rock or porcelain with Motive Stones, or mounting points for Motive Stones, stored in here, this safe seemed chiefly built to hold something other than Nephilic artifacts, something stored in ceramic containers on the shelves, some of them large and cylindrical, others fist-sized spheres.

Petrus gingerly took one of the larger jugs down from a shelf, stepped out of the safe in haste, and nodded for the guard to shut the door behind him. Bringing to a copper-surfaced table in one corner of the room, he began to explain what all this caution was about.

“This, I think, you’ll find useful. It’s a new weapon, one only known to myself, Alexios, the handful of acclaimed scholars and fringe alchemists whose expertise was needed to make it, and an absolute minimum of palace retainers besides. We’ve not yet used it on the battlefield– mainly because it’s best-suited to naval warfare, and most of the Empire’s fighting of late has been done in the desert against the Haxamanids. I think this problem warrants making its existence known, though I would like to keep the recipe a state secret… until the King on High joins the earth back unto the heavens, if any secret can be kept that long.”

He uncorked a small opening on top of the jug, reached in with a small spoon, and scooped a globule of viscous gray liquid onto the tabletop.

Rufio scratched his head. “Your secret monster-killing weapon is jelly?”

Petrus spooned the substance into three puddles, separated by a full cubit. He made a Fire Sign over one: the most basic sign any novice learns first, with the thumb and middle finger held together and the rest splayed out. He snapped, and a spout of flame ignited the fluid.

It flared up, burning intensely and continuously. Even as it did so, Petrus took a pitcher from below the table, and poured a small drop of water onto a second. It, too, went up in flames suddenly and violently.

The third, he simply spread thin over the table with the underside of the spoon, and fanned with his hand. In a moment, it, too, burned, and none of the onlookers could bear to remain in arm’s reach of the table, for the heat the three burning globules gave off. It was at least two minutes before the flames began to sputter and fade.

“Our working name for this accelerant is ‘Rhatian Fire’, but I am open to other suggestions. It will float and burn on water, and stick to skin. An open flame will, of course, ignite it, but so will contact with water, or even exposure over a large enough surface area to open air. It is a mundane substance made from things found in nature, and thus cannot be put out by anything that directly influences the outpouring of magic. A single pot, skillfully thrown, can condemn the mightiest warship to a slow death.”

“Yes,” Valens said, “deft handling can reduce an enemy ship to a smouldering keel… and daft handling do much the same to your own ship.”

“We are working on a mechanism to spray the stuff out the prow of a ship, directly from a storage tank, with no intermediate handling. For this hunt, though, you’ll just need to handle the stuff with care.”

“Hm.” Valens scratched his chin. He already had the beginnings of a plan, but this liquid flame solved more than one of the issues he kept running into. Still, he would have to choose his ground carefully. And to do that… “Do you know of a way to draw the beast out? A favored prey, or some act that tends to provoke it?”

“You may do well to ask sailors on the waterfront about the matter, but my understanding is that ships carrying great quantities of metal– bullion, tools, arms, whatever form– seem to be its favored prey. That may merely be because their heavier cargo causes them to sit lower in the water and to move slowly– easier to catch.”

“I don’t think so. The ship that brought us in seemed to avoid its attention by going slowly. Ships making wakes seemed to draw its ire, not slow ones, from what we witnessed.”

“Then it may well be some other property of metal that draws it. The smell, maybe. That makes me want to give you something else for your hunt, besides Rhatian Fire.”

Petrus returned the jug to the safe, and when he emerged from it, he held an artifact much like the Motive Stone key he had used to open it. This had a much more intricate handle, however, in the likeness of a fish, with an Air Motive Stone set into its mouth.

“Is that…?”

Petrus put a finger over his lips, and hurriedly led them out of the laboratory. Only as they cut across a garden in a courtyard, well away from anyone who could overhear, did he explain, for the benefit of Rufio, Atia, and Hadrian.

“This was found on the corpse of Emperor Euphemios III’s treasurer, after he was shot down in an attempt to defect to Hypatios. There is no doubt in my mind that this is the key to Euphemios’ lost treasury. But I have spent the last sixty years searching for the door it unlocks, to no avail. I’ve tried every inch of the palace, and the Nephilic ruins below it, including the whole length of the ancient tunnel that still runs underneath the strait. I’ve searched the hippodrome, every remotely old or important church in the city, even the city walls. By now, I would consider the possibility that it was buried on a remote beach somewhere along the strait as likely as anything else. If Chrysos is attracted to large bodies of metal, and if you intend to track his movements before laying a trap for him, then there is some remote chance he’ll lead you to the treasury. If we can find it under Alexios’ nose, then we can bribe the northmen, the Blues, the Yellows, and anyone else we need on our side to end the reign of the Hypatioi, before the coup can spill out of these walls and become a civil war.”