Archstone
From Miners Settlement - Game Wiki
The Archstone is a structure found at the far right end of the map, past the Ruins of Elven Temple. It lets you summon and fight Guild Bosses, elemental Dragons that have large amounts of HP. You need to be in a Guild to be able to fight Guild Bosses.
From within the Archstone menu you can see a list of all the available Guild Bosses, giving you the option to summon them if that particular boss hasn't been summoned by a guildmate already, or to enter its combat area otherwise. The cost for summoning is a Summon Artifact purchasable at the Summoners Wall.
You can also access the leaderboard for that type of Guild Boss, with all progress on it being reset at the start of every month.
Created by: Lagopus