Rumblecusp

 is a volcanic island in the Swavain Islands, southwest of Nicodranas and northwest of Urukayxl in the Lucidian Ocean. It was the site of Traveler Con on the 26th of Unndilar, 836 PD.

Description
Dominated by the volcano that gives it its name, the island's shallow white sand beaches and rare trees create a tropical paradise. At a distance, it is dominated by a wild mountain range, with thin switchbacked ridges giving it the odd appearance of an opening flower. In its center rises a massive mountain with a lazy trail of smoke drifting from its peak. The majority of the island is dense, lush jungle, surrounded by a faint ring of white sand beaches against rocky cliffs. The jungle is so dense that it seems to rise and roil with the landscape, rising up over mountain ridges. Some of the trees push up and cause strange tower-like structures that grow much larger than all the others surrounding them. The volcano itself comes to a point, with no caldera visible. There is a bit of an orange glow from a faint magma trickle near the zenith of the mountain, and a fissure from which the smoke emerges.

From the southeastern inlet, a faint mist lies over a large portion of the outer jungle, giving the island an almost dream-like quality. Beneath the water are sandbanks that wind out beyond the beach, looking like white tendrils beneath the ocean. Rising above the mist, the trees are extremely tall, a hundred or more feet up with thick trunks. A little further in, on the path toward the base of the massive central volcano of Rumblecusp, is a clearing holding a small village.

Viridian, one of the leaders of the village, described the island as the central focus of the world, home to many strange slivers of different parts of the world that create the land mass. Beneath the trees are odd landmarks that shelter dangerous beasts that might be a surprise to find on the ocean, a number of unnatural dangerous denizens. To cross the island, moving carefully, she estimated would take a few days, and about eight hours to reach the base of the volcano from the village.

Vo Village
The village, known as Vo, consists of about two dozen or more structures built across the ground and into the tree canopies themselves. There are networks of ropes and other long pulleys and cords that are bound between trees at a distance, and there are buildings held aloft about fifty or sixty feet off the ground, with bridges connecting them. Elements of it appear to be built of driftwood, or carved from local trees, or from pieces of ships that have been scavenged. The villagers wear tattered clothing, leathers, skins, hide, rusted chain, and nothing else. There are no accessories; it is bare-bones basic attire. There is no decor bringing it beyond anything functional. There are heavy ropes tied to the higher trunks and branches, a massive tangle of treehouses built of makeshift scavenged materials, ship parts, local lumber, and intricately woven and grown vines and dried vegetation. A third of the buildings are built up above at different levels connected by bridges. Most of the structures are supported by thick, healthy green vines, braided, entwined, and tended to hold and wrap them as it the jungle itself had risen to support and help hold the village together, structure to structure. The buildings are diverse in styles, materials, and apparent age.

A central massive tree marks the middle point of the village, lush and perhaps 200-feet tall, with numerous levels of branches. In each of these branches, the vines have grown out to clutch another small homestead almost like a hand, and all of them have connected vine bridges. It resembles a high elven establishment mixed with nature, deliberate and balanced with the natural world around it.

The Winding Core
The Winding Core runs from the northwestern side of the island underneath the mountain and then comes out on the southeastern side, which is where most of the villagers' mining is done. It is the location from which they mine beautiful gems, diamonds, and "various gifts from the land that we can refine". The Winding Core is also an entrance to the Underdark.

The Shaded Tangle
The Shaded Tangle lies along the path towards the entrance to Vokodo’s lair within the mountain itself, a cold place where color seems to be muted, where the mists grow cold. There is no sound of any birds or insects, and the temperature drop and loss of color feels supernatural, as opposed to just a barren location. This is probably caused by an opening to the Shadowfell, causing the plane to bleed into the area and bringing new wildlife and creatures on the island.

The Ruin
The Ruin lies far to the north on the island in the middle of an area of gray, rock-filled emptiness that once held jungle that has now rotted and then petrified. A heavy fog shrouds the entire region. There are a number of broken buildings like a small village. Some structures are mostly intact, but some are bare bones exterior, the corners and the bare remnants of where they once stood. In the center is a singular large obelisk-like spire that is a sheared off portion of a tower.

The buildings of the Ruins resemble those in the Ghostlands on the outskirts of Rosohna. Sheets of ice form on their edges and the temperature becomes quite cold. The creatures within the ruins whispered of Oracs, suggesting that the ruins are a shard of the Blightshore city of Ghor Veles where Oracs lived.

Swarms of mosquitoes and groups of undead tree-like creatures roam the location. A large ghastly creature, as well as a group of spectral figures, occupy sarcophagi within the spire. The bodies were buried with ornamental armor, weaponry, and trinkets, and Infernal script is detailed across the building and sarcophagi. The spectral creatures also spoke Infernal.

Heaven Falls
Lying to the northeast, the Heaven Falls are forbidden to the villagers by Vokodo and are a mystery to the Vo people. They protect the ocean entrance to the interior of Vokodo’s lair with a waterfall that falls about 150 feet toward the sky before curling into the mountain itself.. It arises from a rift to the Elemental Plane of Water from an opening at the bottom of the lagoon, before it breaks upon the cliff face, separating into small rapids, rivers and waterfalls that spill into multiple pools.

Behind the waterfall, there is a tunnel in the cliff face hidden by an illusion. The tunnel leads to a large cavern filled with multiple ships. According to Viridian, when travelers decide to stay on the island, they are instructed to leave their vessels there. Beneath the water in this cave is another entrance to Vokodo's lair, similar to the one on the other side of the island.

Vokodo's Lair
Vokodo's underwater lair lies deep under the volcano, reachable by only a few hidden and guarded passageways. The entrance normally used by Viridian runs through an area of poisonous gas before reaching a pool filled with breathable water. Beneath the pool is a tunnel lined with dangerous torchblooms from the Elemental Plane of Fire that leads downward to a gargantuan (at least a hundred feet across) underwater chamber of rough black glassy volcanic rock broken by heavy patches of torchblooms giving off pockets of light, in which Vokodo lurks. Some of the rock walls glow faintly orange with heat from the proximity of the volcanic activity. The torchblooms lining the tunnels can close them off when visitors are within the chamber.

Whenever someone wanders too close to an entrance to the lair, there is a chance that they will become inexplicably drawn to the center chamber where Vokodo resides and know the exact way to get there.

After the Mighty Nein and Adella's crew garviously wounded Uk'otoa, and Zehir resealed him, entruting three renewed Cloven Crystals, Fjord hid one of them in Vokodo's lair.

Society
The Explorer's Guide to Wildemount states that only a few dozen people inhabit the island, and Pono estimated there were close to seventy when the Mighty Nein arrived there. However, Vilya stated later there were close to 120. The island has been populated for ten to eleven generations.

The people of the island worshipped Vokodo, and referred to him as a great fire god. The villagers referred to the great volcano of Rumblecusp as "Vokodo," stating that Vokodo both existed within, and was it. When newcomers get settled on the island, they had to visit Vokodo at least once and give him a valuable gift to be accepted. The villagers had to constantly give precious items to Vokodo to keep him satisfied, and in turn, they believed he would keep them safe and provide for them. Because of this, they do not own many material possessions outside of basic tools and furnishings. Their main activities seemed to be mining and refining jewels and precious stone to give to Vokodo, and hunting and fishing for their food. They eat communal meals.

The Vo were led by three people who made important decisions together. The last known leaders were Viridian, the spiritual leader; Terra, in charge of hunting; and Lukash, in charge of infrastructure. The spititual leader of the Vo travelled to Vokodo's lair at regular intervals to bring him gifts in the name of the entire community.

Everyone in the village seemed unable to recall who they were and where they came from before settling on Rumblecusp, although they did not seem to question it. After Greater Restoration was cast on Viridian, she regained her memories and revealed that something on the island made people forget who they were to ensure that they remained there to serve Vokodo. There are several children in the village who where born there, implying that many adults may have also only known life on Rumblecusp.

After Vokodo's defeat, all inhabitants of the island regained their memories. Many of them immediately planned on going back to their old life, while some decided to stay.

The Mighty Nein arrived on the island (fleeing from a dragon turtle) in preparation for Traveler Con upcoming in slightly over a week. They encountered several displacer beasts that were routed by two werebear inhabitants of the island, whom they befriended, and were led through the jungle to the village of the Vo people, followers of Vokodo.

The party are told by Viridian about various locations on the island and about Vokodo, and that they needed to meet with Vokodo to gain his permission to hold Traveler Con. In the morning, she guided them along the path toward Vokodo's lair.

The Mighty Nein and Vilya traveled north toward the volcano and Vokodo's lair, passing through a sliver of the Shadowfell, fighting a bodak and will-'o-wisps, and hiding from a tyrannosaurus and a draegloth (native to the Underdark). In Vokodo's lair under the volcano, they swam through tunnels lined with torchblooms native to the Elemental Plane of Fire and spoke with the "god", offering him valuable items in exchange for their release.

Vilya told the party that she arrived on the island from the Elemental Plane of Water, landing semi-conscious at the Heaven Falls waterspout, which is forbidden to the villagers. The party then traveled there and discovered a back door to Vokodo's lair hidden in an illusory cliff face behind the water rushing upward from the Water Plane. Exploring within, they found an immense cavern filled with the ships on which the now-villagers arrived on the island.

Caduceus's Divine Intervention succeeded, and the Wildmother sent a vision of Vokodo in his home plane of the Astral Sea running in terror from something chasing him. He crashed through the barrier, dragging pieces of other planes with him when he landed on the island. He both changed the island by his arrival, and was changed by the volcano he now called home. The party traveled north to The Ruins, evading undead tree-creatures along the way. The Ruins appeared to be a sheered off section of the Blightshore city of Ghor Veles, inhabited by tomb spirits and Lord Cioro, a wraith, whom the party fought and defeated.

The Mighty Nein and Vilya traveled back to Heaven Falls to rest and prepare for the upcoming battle with a Heroes' Feast. The next morning, to try to draw Vokodo out of his lair, the party set multiple ships on fire but the only response was a growl and that the volcano began to erupt. The party immediately assaulted Vokodo in his lair, and after a hard-fought battle, Vokodo fell.

After the Mighty Nein defeated Vokodo, they escaped his lair with a large amount of the treasure horde formerly located on his back. The group was safely transported to the outskirts of the village by Vilya, who walked into it to assess its current emotional state. With the villagers' memories restored, tensions were running high, with suspicions of each other, awkward conversations, and frantic packing. Many of the villagers decided to leave the island and return to their families at home, but many also decided to stay.

and
The islanders prepared themselves for the massive influx of visitors to the island of Rumblecusp in celebration of the Traveler. Progammed illusions were placed all around the island, a stage was set up for musicians to play, and the Mighty Nein hunted down a T-rex for food. As the days grew closer to the event, Artagan showed himself a few times to the group and asked them how to fake his ascension. Eventually, they settled on the idea that the Traveler was just the Moonweaver in disguise.

Flora

 * Strange flowers: When Yasha smelled a purple one, she felt compelled to eat it, but her strong constitution shrugged off the presumably negative effect it would have had on her. She was able to press an orange one into her book of flowers.
 * Carnivorous vines: Thin vines that dangle straight down, almost like curtains, that turn reddish at the tip. They are covered in tangled strips of decaying flesh holding an occasional bone.
 * Torchblooms: Native to the Elemental Plane of Fire, these plants grew in the entrances to Vokodo's lair and shifted to allow or block the entry. Torchblooms deal fire damage if touched and are bioluminescent.

Fauna

 * Displacer beasts
 * Dinosaurs
 * Deinonychus
 * Tyrannosaurus rex
 * Bodaks
 * Creatures that live beneath the ground and exude a sticky substance into a pool above them to trap the unwary.
 * Ghosts
 * Will-o'-wisps
 * Draegloth
 * Mosquitoes and other carnivorous insects
 * Undead shadow creatures in the Ruins
 * Undead treants
 * Wraith

Trivia

 * While Vokodo lived, everywhere on the island, there was a creeping feeling of being watched. After flying away from the coast for fifteen minutes in a straight line, Beau and Jester could still feel the gaze on them.
 * The island was covered in a dense mist that dissipated after Vokodo's death.
 * The memory loss seemed to only begin to take effect when waking up after the second night on the island. On their second morning, Fjord, Jester, Caduceus and Yasha woke up with many missing memories of important events and loved ones.
 * Every morning when waking up from a long rest, the Mighty Nein noticed that some of their items had completely vanished. Somehow the items in question made their way to Vokodo.
 * The island has several shards from multiple planes due to Vokodo crashing onto Rumblecusp.
 * Sam started the running joke of referring to the villagers as the "V.O. community" (voice-over community), a nod to the fact that all of the cast members are voice actors.