Heroes of Yggdrasil, the One Tree

In Norse mythology, Yggdrasil is the great multiversal tree that is linked to all dimensions of reality. In Heroes of Yggdrasil, the One Tree comes to life in a unique and unexpected way: it is a living planet floating in space, upon which our adventure takes place. It is so huge that each of its leaves is the equivalent of a region hundreds of miles across and each branch is a country. Despite the exquisite natural and magical balance of life on Yggdrasil, dark forces seek to destroy its very foundation of life. Will heroes rise up to prevent catastrophe and the destruction of the One Tree itself?

Yggdrasil was the first living being in the universe. A non-sentient concentration of life, its growth was sparked by the magic infused in the birth of the universe. Over millennia, life forms evolved on Yggdrasil, just as they have on many planets in the universe. The pantheon of gods from classic Norse mythology arose from the magic of the tree, dedicating themselves to different aspects of existence, from wind and water to storms, battle knowledge, and wisdom. Worship of these deities as well as prominent Druid-led worship of Yggdrasil itself is widespread across the tree.

Over time, nations have arisen. Some branches and leaves are wild and untamed, while others have become small states or countries. Diverse forms of political rule exist, from tyrannical autocracies to egalitarian democracies. The wealthiest and most powerful of the nations are those that have united expertise in mining, with a focus on specialized teleportation magics that have allowed them to plunder the distant asteroids that circle the tree. Dwarven, Kobold and Human nations have become dominant powers, but the tribes of Dragonborn have also positioned themselves as global players.

Two secret organizations have gained power over the years and compete with other communities on Yggdrasil. The cult of Loki, which is known as the Horns of Loki, is a mix of rogues and clerics who set out to undermine organized society and cause chaos. They also have long-term plans to trigger Ragnarök to gain revenge for their god. A second community that vies for power are the hags. Their society is called The Hagafia, and they have perfected the arts of transformation, illusion, and disguise, allowing them to infiltrate all major nations around the tree. With well-placed agents everywhere, and magical communication methods via cauldrons, they slowly tip the balance of power in their favor and bide their time.

Lastly, a third power endangers all life on Yggdrasil. A demon from the plane of the Abyss known as Orcus has conquered a dimension known as Mechanus, where Constructs are built. He has established a corrupted process whereby Demons and Constructs are combined using necromantic magic, and he has been carefully unleashing them via portals onto Yggdrasil, furiously jealous of this source of life. The Demon-Constructs carry toxic demon blood, which they have been using to poison farms, rivers, and seas. And Orcus has dark plans to escalate the destruction…

The One Tree is the source of all life. As it floats in space, it circles around the sun, with its topmost point closest to the star. As a result, the branches closest to the top of Yggdrasil are tropical, and the middle zone is temperate (the majority of humanoid races live there), while the roots of the tree are covered in miles of thick ice—indeed, comets and frozen ice chunks from space are embedded in the roots. Water rises through tree veins, which are so big they stream like rivers (and intelligent species have torn them open to use them as such) and collect in great seas.

Dirt has built up on the surface of leaves over millennia as particles from higher leaves and bark fall to form topsoil, where plants grow. Caverns can develop hundreds of feet down into the earth and leaves can be up to 1 mile deep in parts of the tree.

Gondolas on pulleys are used to travel between branches, while vehicles with hook wheels and swing seats can travel on the trunk itself. The flying races are experts at traveling from leaf to leaf so they can be hired as navigators to lead groups using parachutes or gliders.

Leaves are identified by a name plus a number, the number indicating how far from the trunk they are, with lower numbers being closest to the trunk. While lower branches have less light exposure overall, across the whole tree, there is no night or day. Due to a slight wobble in the tree’s rotation, upper leaves can shade lower leaves randomly. At any given half-hour interval, the gamemaster rolls on a random table to determine the degree of darkness outside. Despite this, time is broken up into eight-hour increments for a day of 24 hours because the tree rotates every 24 hours.

An outline for the populations on nine branches and 19 leaves is provided below, as well as maps for eight of the leaves:

An outline of the populations on nine branches and 19 leaves.

Bindelstaff 8.

Serando 8.

Bellvanlaika 61.

Chassenum 62.

Vekmugnark 12.

Jafavdack 2.

Fistogon 11.

Refraxia 50.

There are two master fronts that players will need to confront to prevent destruction of the Tree. Both have a series of events that will grow in danger and severity over time as players grow more powerful. The fronts will also intertwine and give players the opportunity to make independent decisions on how and where to address the dangers they face.

Players begin their lives on the leaf known as Bindelstaff 8, either in the city of Bindelstaff or in the surrounding countryside. To create a more immersive experience, gamemasters should work with players to create backstories and relationships for each of the characters, as well as personal connections to the leaf Bindelstaff 8. Also, some characters, but not all, should have a connection to one of the Norse gods, the Hagafia, or one of the other primary factions.

Primary Front One

The Demon-Constructs poison the tree with toxic blood, and players must stop them before Yggdrasil itself collapses.

• Knife-armed Demon-Constructs drop onto farms on Bindelstaff from above, killing farmers and poisoning their land entirely.
• Ruins on a leaf above Bindelstaff—Serando 8—are revealed to be a staging ground for their assaults on the leaf below.
• Clues lead to the discovery that an asteroid is where Demon-Constructs are being prepared for attack; the players must teleport to the asteroid and destroy the bizarre demon hybrids who took over this mining site from the Kobold nation.
• Rivers and seas become polluted as Demon-Constructs poison them.
  Sea creatures mutate and then attack boats and fisherfolk.
• Food shortages become widespread, leading to riots and starvation.
• Players discover that more powerful Demon-Constructs have been burrowing through leaves, stems and branches, attempting to undermine the physical stability of Yggdrasil.
• One leaf stem that has been hacked through falls off its branch, crushing an entire country of people.
• Players eventually track down these monsters and destroy their source, but then, tree-wide water supplies begin to shrink.
• Players track the source to the roots of Yggdrasil, where an immense Corrupted Purple Worm/Demon-Construct hybrid is chewing through the roots.
• Finally, once the players have reached their highest level of power attainable, they travel to Mechanus itself and evict the demon overlord, Orcus.

Primary Front Two

Squash the Horns of Loki in their efforts to sow chaos and bring about Ragnarök.

• Whichever player has the strongest connection to a Norse god is betrayed by a leader in their temple, who is secretly aligned with the Horns of Loki; this betrayer becomes a nemesis NPC until the players can finally defeat them; the GM should continue to level up this nemesis as the Player Characters grow to keep them challenging.
• Key players might be imprisoned and prepared for ritual sacrifice by their nemesis, in which case a rescue must be staged.
• Players uncover a connection between a thieves guild and the Horns of Loki.
• 25 years ago, there was a major war that impacted many branches: the Ogre War; the Ogres’ nemeses, the leaders of the Horns of Loki, are plotting to trigger a second Ogre War.
• A Frost Giant hired as a mercenary by the Horns meets with large Ogre tribes to encourage them to attack the human nation of Elgoreth, of which Bindelstaff is a part.

Plots within the plot: the Horns of Loki have a secondary secret purpose, and the second Ogre War is a ploy to get their hands on the great Jotunn Horn, which is kept in a vault in the human capital.

• The Jotunn Horn, if blown, will awaken a 300 ft tall Jotunn, who has been sleeping for centuries.
• After it awakens and begins to ravage the countryside, the Horns will have access to the cave blocked by its sleeping form—this cave is a path to the Underworld, where they will travel to free the great wolf Fenrir and thus trigger the beginning of Ragnarök.
• Can the players interfere with their plans?

I have also designed numerous Encounter Maps. Below are some 3D images of just a few of the encounters I've built so far.

Wood Elf Ruins.

Chapel in the Secret Temple of Loki.

Surprise attack of plant Blights.

Fight with the Lake Troll.

Scenes for the asteroid assault. 1/4

Scenes for the asteroid assault. 2/4

Scenes for the asteroid assault. 3/4

Scenes for the asteroid assault. 4/4

Part of an Elven treehouse.

A flying warship.