- Spheres: Each of the thirteen spheres is identical, crafted of solid iron and floating in the sky around the main tower. A Large air elemental is bound to a single Khyber dragonshard that sits atop each sphere. This provides the spheres with their ability to float, though their positions are controlled from the tower.
The spheres are constructed with three rotating rings, each of which can be manually set to one of thirteen positions by any creature that can fly to them. Runes representing each of the thirteen moons (twelve extant, one historical), the thirteen planes of existence, and the thirteen Siberys dragonmarks (including the lost Mark of Death) line the rings.
By manually rotating each sphere’s rings to one of 2,197 runic combinations, a creature can attempt to fine tune its ability to scry from inside the observatory. A DC 25 Knowledge (arcana) check can tell an observer how to set each sphere’s rings in order to add a +2 circumstance bonus to the DC of any scrying spell cast from the observation room (including using the main scrying crystal; see below). Every 10 points by which the check result exceeds the DC increases this bonus by +1, but the rings must be reset each time a different target is scried upon.
- Observation Room: This room is filled with instruments of all manner and design, with strange crystalline and metallic gauges giving readings that few understand. The center of the room is open to the control room 60 feet below, allowing a dragon to hover between the two floors. Creatures unable to fly will need to find their own means of safe descent since there are no ladders or stairs.
A large crystal in the center of the south wall serves as the observatory’s main scrying device. In order to use it to scry a particular target, a character must first determine which of the observation room’s hundreds of controls need to be adjusted. A DC 30 Knowledge (arcana) check allows the character to determine 2d6 controls that will attune the observatory for scrying on one particular target (roll again for each new target selected). Aligning the crystal then requires the manipulation of these controls, scattered around the edges of the room. Since they were designed for dragon use, each control requires a Strength check to move (DC 3d6+15; roll separately for each control device). Once all the controls have been set, the main crystal can be activated as if it were a crystal ball with both telepathy and true seeing.
Any attempts to use the observatory to aid in divination must be made from this room. See page 272 of the EBERRON Campaign Setting for information on the uses of a Siberys observatory.
- Control Room: This room contains thirteen massive metal rings, each mounted to rotate and swivel as necessary. A DC 30 Strength check turns any one ring in order to move one of the spheres that orbits the tower. A DC 15 Knowledge (architecture and engineering) check allows a creature to move each ring in order to obtain any particular arrangement of spheres, including moving a given sphere adjacent to the balcony on the western side of the tower. From the balcony, the runic rings of the adjacent sphere can be rotated by creatures unable to fly.
By studying the rings in the control room and making a DC 30 Knowledge (the planes) check, a character can learn how to attune the observatory to a specific plane of existence by arranging the spheres’ position. Each plane has a different arrangement, and thus requires a separate check. While the spheres are so arranged, all divination spells cast within the observation room (or using the main scrying crystal) can target creatures and locations on that other plane as if the casters were on that plane themselves. Any creature that plane shifts from the observatory to the attuned plane appears only 1 to 100 miles from its intended destination (rather than 5 to 500 miles). As well, if that plane is currently remote, the creature gains a +3 circumstance bonus on the Spellcraft check to successfully reach it. If Tyrass (or an intruder) has plane shifted from the observatory, it is possible to deduce his intended destination by noting the arrangement of the spheres and making a DC 25 Knowledge (the planes) check.
A large hatch takes up the center of the floor in this room. It is sealed with a complex lock of concentric metal rings. A DC 30 Open Lock check can unlock the hatch and grant access to the prophecy room. - Prophecy Room: This chamber is almost entirely empty except for a large pile of five thousand copper coins (which serve as a resting place for Tyrass when he is ruminating) and a number of large scrolls written in Draconic. The most interesting aspect of the room, however, is the layer of soft reddish clay covering the walls. Here, Tyrass has written most of the knowledge he has of the Prophecy in abbreviated Draconic.
Hundreds of thousands of claw marks make up a dense mass of writing that would literally take a lifetime to translate. Portions have been rubbed out as Tyrass learned new information and corrected previous mistakes. Any character who can read Draconic (or use comprehend languages or similar magic) can attempt a DC 30 Decipher Script check to understand a specific portion of Tyrass’s shorthand in the loosest of terms. The meaning, however, is always circumspect and difficult to comprehend, even when translated to Common.
- Lair: Tyrass’s lair is located beneath the tower proper in a large empty cavern. There are no physical entrances to or from this room; Tyrass uses dimension door to reach it when necessary. It is located 300 feet below the prophecy room and has an alarm spell cast on it every morning while Tyrass is in residence. When Tyrass is near, a massive pile of gold and platinum lies here—the bulk of the dragon’s hoard—plus any magic items that he does not keep on his person. Dozens of scrolls of both arcane and divine spells sit in a pile in the corner. If defeated in battle, Tyrass will teleport here and retrieve enough scrolls to heal himself and gird against his attackers. If the dragon is traveling on another plane, the most valuable portions of the hoard reside in his portable hole, which he keeps with him at all times.
An iron golem (crafted from an iron golem manual Tyrass once acquired) guards the lair, automatically attacking all creatures aside from its creator.
