A free mod for Valheim, by AngryChild.
This mod lets you play in a world with a map. The map contains a lot of locations and objects. You can go to these locations to gather gear and resources. Once you've collected enough gear, you can start the invasion.
In the world of Raidheim, you can build your base. From this base, you can craft and smelt ores. You can also fight bosses. These bosses contain more powerful enemies than normal enemies. It's not easy to beat them. It's recommended to fight them with a friend.