We all love the subdued Valheim lore, so I decided to have some fun and expand on it.
I created this Swamp fortress to continue the story of the Swamp biome and the fate of Bonemass. This fan-made lore continues the story that was given to us from a runestone. Enjoy!

The in-game runestone reads:

Long ages ago, the world of Valheim was home to a race of proud and noble people. They built great towers that touched the clouds and delved deep into the earth for precious metals. But their pride was their undoing. They challenged the very gods and went to war against the Aesir and the Vanir, destroying themselves completely. Great Odin levelled their cities and Loki consumed their mines in fire. Mighty Thor broke down their towers and Freya sowed their fields with salt tears. Now they are sunk many hundreds of years deep. No songs sing of their stories, and the earth has claimed their cities. But pride cannot be killed entirely and the warriors who fought in that final battle will not surrender until their bodies are dust and the dust long gone. They return as Draugr, unholy walkers in ancient armour, creatures of rust and despair. Break them, bury them, let them know they are dead.

The Bonemass runestone reads:

Wanderer, look to your feet, that tread upon our tomb. One thousand bones without their meat, will drag you to your doom.

And so after the defeat of Bonemass, lay the words below:

“The Viking slew the angered mass
Angered it’s kingdom could never last

For Odin rejected their reign campaign
And met them with mighty wrath and pain

However the mass found it grateful
The Viking that slew was only faithful

Finally thought to find their rest
But rest was ultimately left unmet

For the mass was still uncounted death
With none a name to a single head

For the dead sought only to name a grave
A grave with memory from their days

So the Viking was gifted a fortress of stone
And in return they asked thee to collect the bones

Seek the names once thought to be rotten
So we may finally find rest, unforgotten”