Castle Blorpy will come to rest on a small mountain top, in the crater it left the last time it was here.... the creation of defensible walls is a beneficial side effect of the castle's mode of travel. Visible nearby is a large glacier, a sheet of ice. Several miles across the glacier a large anomalous hole is visible, of unknown depth. This is the destination, roughly two hours of travel will be required. Each hour, the PC's will need to make a DC 10 Constitution save to avoid a level of exhaustion if they don't take preparations against the cold, and the constant freezing wind gives disadvantage on Wisdom (Perception) and ranged attack rolls.
1-3) An ice hazard, DC 15 Perception to spot, fall 3d6 (DC 15 Athletics or Acrobatics for 1/2 damage.
4) A mated pair of Yeti will stalk the PC's, attempting to get close and ambush them. (AC-12, HP-55, +6 x2/1d6+4/1d6 cold)
5) A strong blizzard blows in, requiring a DC 15 Con save to avoid 1d6 cold damage and a level of exhaustion per hour, lasting 1d4+1 hours. DC 10 Survival roll will allow the PC's to find shelter for the duration.
6) A visit from an Adult Silver Dragon, "Myndyrth", which will take the form of a large snow-eagle. The dragon will simply observe them unless they appear to be evil or in distress. It recently slew the white dragon that ruled the glacier, and left it's carcass on the ground where it fell. This will only occur once.
7) The carcass of an adult white dragon, broken as though fallen from a height, and rent from battle. This will only occur once. A group of wandering orcs led by an orog have claimed it, and will fight the PC's whether they want to or not. This will occur only once. orog have claimed it, and will fight the PC's whether they want to or not. This will occur only once.
8) A group of wandering orcs led by an orog is looking for a fallen dragon and its lair in hopes of looting it. All are wearing hide armor (AC-13, except the leader in chain mail.orog is looking for a fallen dragon and its lair in hopes of looting it. All are wearing hide armor (AC-13, except the leader in chain mail.
9-12) No encounters or hazards this hour, just ice and wind.
Miles from the castle the PC's will discover a large hole in the ice about a half-mile wide, surrounded by walls of solid ice about a hundred feet high. Ice rubble piles and melts at the bottom of the walls, but within the oval enclosure it is ice-free and quite temperate. Visible within is a lush, green forest, with several artificial structures within. Getting down to the ice valley will be difficult, but as long as they don't hurry, it can be done. They may also observe tunnels leading out of the ice wall, that may allow easier access.
Natural steam vents, water drainage, and the activity of intelligent agency have created a few tunnels from the edge of the glacier to the center. The twisting maze is home to a group of Yeti that hunt the mountainside near the valley, though they rarely enter it. They will follow the PC's into the caves, but if they make it to the rift alive, they will not pursue them. If the PC's follow the flow of water, they will eventually come to the exit, 30ft up the wall above a shallow pond. If the PC's jump in, or if they slip and fall, they will find the water surprisingly warm and pleasant.
The Sylvan Forest: This woodland appears to be a slice of the Feywild. Surrounding the ruins is a large river which appears to flow into itself perpetually, and even includes a couple of dramatic waterfalls that make no topological sense. Crystal bridges cross the river in a few places. Most of the forest is strongly Fey, but as long as the PC's remain on the trails, they should be alright. Faerie Dragons, Dryads, Displacer Beasts, Awakened Trees, Cockatrices et cetera all call the forest home and have little concept of the world beyond the ice walls or the passing of time. There is even a circle of brightly colored, sun-dwelling myconids. When the occasional monsters from outside blunder in, the forest creatures usually wind up killing them or driving them off pretty quickly. The various creatures are descendants of the creatures created by the Elves for their own inscrutable purposes, and none of them have an outside agenda beyond existence.
Random Encounter:
1) A mated pair of cockatrices has wandered along, looking for prey. The PC's will startle them, leading it to immediately attack the closest PC.
2) A small group of yeti has climbed down the wall, looking for prey. They will attempt to kill one person and take them away to be devoured.
3) A patrol of 1d4+2 animated armors will come upon the group, decide that the PC's are intruders and will attack immediately.
4) A group of wandering orcs led by an orc shaman (Groo) noticed the castle, and have followed clues to wind up here. All are wearing hide armor (AC-13), except the leader in chain mail. They are accompanied by an Ettin who will attack regardless of the situation.
5) A goddamn phase spider.
6-12) Nothing much in here besides what is described.
The Ruins: The Elven ruins are largely collapsed from the effects of time, though the gates themselves are still intact. Everything is overgrown with vines, like a garden grown amok. Foundations of smoky crystal, graceful arches, pillars with worn relief art, all can be found in great quantity. Within crystal sarcophagi, elven bodies can be seen entombed inside solid gemstones. Eventually, the PC's will find evidence of intruders coming through the gates - mostly bones and bits of armor and weapons scattered about. Some of great age, some more recent, and some unidentifiable. Nothing newer than decades old can be found. Intruders are usually dealt with by Animated Armors, but as time goes by, fewer of these defenders remain intact. They will attack the party as well unless someone with Elvish ancestry orders them to stop - in Elvish. This will get the armors to pause, for a short time.Like many Elven ruins, this site was a small settlement, a manor of sorts too small to be directly targeted in the cataclysm, and too isolated from the outside world to be interfered with. The main "building" is simply a gracefully covered hexagonal pillar with a doorway that leads to a spiral staircase. This comes through the floor of the "Main" room, which itself has six doorways to other rooms. Most of the doorways are simply to rooms that are actually located in null-space. Most of the rooms are quite mundane for an extradimensional space, though the fabric of reality is getting a bit weak in some of them. Each room except the gate room has a series of doors that connect it to the other rooms. All of the rooms are overgrown with vines and covered with leaves and detritus, showing signs of neglect. Throughout the complex are small light globes which produce a soft clear light when in the presence of a living being. If removed from the complex, only 1 in 6 will still function, but they are quite valuable as gems.
Interior Conditions - Elven "Animated Armor" is lighter and faster - AC-16, +6 to hit, and 1d8 slashing and piercing damage due to the rapier blades on the arms. Even worse, they "Blur" when on the attack, making attackers suffer disadvantage. It is quite sleek looking but will be useless once defeated. There are several such armors in the complex. Now and then, creatures wander in from the forests outside, and if they don't do anything to the furnishings, the armors will not harm them. Likewise, the servitors who maintain the site have long since wandered away.
Living Room - The room is and has an ominous quality to it, even upon approach. Assorted crystalline furniture, all quite delicate looking but extremely strong. Some of it is smashed. The room is haunted by a Ghost, the angry soul of a barbarian who found this place and was slain by armors. His corpse can be found in a corner, mummified by dry, largely sterile conditions here. He has a +1 shield and a +1 battleax. When anything of value is taken, he will attack. Two shattered and battered armors, obviously destroyed by the barbarian, lay scattered around his corpse. Along one wall is a large crystal and platinum mirror, which can be used to either cast Scrying (DC-17), or on an Arcana check, can be used to turn any tale that the user knows into a picture play.
Bedroom - Actually there are several sleeping chambers here, each one with more crystalline furniture and a bed. Adjacent to each one is a small pillar with three seashells. If two of the three are touched, an unpleasant reaction will remove all waste (and poisons) from the user's body (CON save or stunned for 1d6 turns), while the third will leave the toucher feeling quite refreshed (advantage on CON saves for one hour). The bed chambers each contain a dessicated elven corpse, each in spidersilk robes worth a small fortune in any major city. There are otherwise no threats or treasure.
Armory - More of a security room than simply an armory, this room holds four inert "animated armors", which will attack upon entry. In various displays is the harness of an Elven Knight. A suit of adamantine scale armor (crits are normal) of uncanny design sits on a rack, and an Elven greatsword enchanted to give Advantage on any attacks against aberrations, but no bonuses. Finally, there is a Helm of Warning, functioning like the Weapon of Warning on p.213. All of these items had many enchantments, long since faded. The Animated Armors will obey the wearer of the Helm, so long as commands are given in Elvish, if they can make a Charisma check of DC 12.
Kitchen Gallery - Many alcoves and nooks. More crystalline furniture and food preparation surfaces, and some indestructible Mithril plates, bowls, and dining utensils scattered about the floor. These are individually quite valuable if they can be gathered up. There is a single large cabinet for food storage, with fresh game inside, preserved by Elven time magics. A cockatrice has made a nest in here, scattering most of the utensils while chasing its prey.
Dining Room - A table and chairs similar in design to other furniture, seating for ten. On a small table along the wall are a mithril platter and several goblets. The bottle holds Elven mead. Once opened and removed from the valley it will soon decompose into sweet but mildly toxic syrup. While fresh, a glass will heal 2d6 in damage and refresh as a short rest once per drinker per day. The bottle holds eight drinks worth of mead and is quite valuable on its own to collectors.
Gate Room - All of the stairways to the gate room arrive through the same gate while exiting through that stairwell will take a person only to the room they desire... if more than one person is within sight of another, the stairway simply leads to the central pillar. This is a circular room, with several portals - each one a mithril archway with small steps leading up to it. In the center of the room is a small crystalline globe, the equivalent of an entertainment center. Activating it requires an Arcana check. Anyone attempting to use it without making their Arcana check first will take 1d6 psychic damage as a result. Success allows it to be used as a Scrying spells once but requires a short rest before using it again. Used as a focus, it gives Advantage to any divination spell cast while peering into it. All of the gates are ancient and have degraded over time. Anyone going through must make a DC-15 CON save to avoid 1d6 psychic damage and being affected by Faerie Fire for 2d6 minutes.
Gate 1: Deoron Gate - Deoron Gate and Saridorn, located in Silverwater.
Gate 2: (MORDOR JUNGLE) A gazebo located deep in the mountains at the center of the Mayhar Peninsula, not far from a hobgoblin city. It is a single destination gate, returning to this location. It formerly led to an agricultural area, now long returned to wilderness.
Gate 3: A malfunctioning gate will dump the traveler into the Ethereal Plane, though unless the character is a planar veteran, it will be hard to tell. It is possible to get lost here. The gate will appear as an identical gateway in the mist behind the PC. After the first time the gate is traversed, anyone in the room will be attacked by a phase spider. This gate is the source of some the weird critters living in the complex.
Gate 4: (JAPAN) Ruins similar to the Deoron Gate, but located in Taohuan territory, in the "Twenty Kingdoms of Pulo Rusak". Use Alt-Onin as a guide.
Gate 5: A small intact single-gate complex on the distant island of Hayak Gandun, partially covered by ashfall.
Gate 6: A gazebo located in the desert in Uthman lands, in the southern reaches.