This page covers the configuration of settings.yml. You can also view the default settings by opening Boss.jar file and viewing the setting files from there. Keep in mind you can't edit them inside your .jar file.
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Folder structure
After the installation, your Boss folder should look like this:

bosses/ - A folder containing individual settings for each Boss.
locations/ - A folder with locations you create with /boss tools.
regions/ - A folder with regions you create through /boss tools.
spawnrules/ - A folder with different spawn rules. Do not edit, this is managed through GUI.
lang/ - Appears after you run /boss dumplocale. Holds the message file you can edit.
data.yml - Internal data file. Machine-generated, do not modify.
unloaded-bosses.yml - Bosses recorded in unloaded chunks, used for world limits. Machine-generated.
settings.yml - The main configuration file.
Automatic Update
Boss updates your configuration automatically and seamlessly. When you update to a new version, all of your configs will get updated automatically.
Keys worth knowing
| Key | Default | What it does |
|---|---|---|
Spawning.Air_Spawn | true | Right clicking air with a spawner egg spawns the Boss in the distance |
Spawning.Air_Spawn_Max_Distance | 30 | How far that reaches. Over 50 blocks loads a lot of chunks |
Spawning.Location_Spawn_Nearby_Player_Radius | 30 | Location rules need a player this close. -1 disables the check |
Spawning.Nearby_Spawn_Min_Distance_From_Player | 5 | How close to the player the Randomly Around Players rule may drop a Boss |
Spawning.Count_Unloaded_Bosses_In_Limits | true | Count Bosses in unloaded chunks against world limits. Paper only |
Spawning.Live_Updates | true | Push menu changes onto Bosses already alive in loaded chunks |
Spawning.Integration.Lands | true | Do not spawn in Lands areas that have mob spawning off |
Fighting.Retarget_Chance | 0% | Chance a Boss switches to whoever hit it |
Fighting.Disable_Cheats | FLIGHT, GOD_MODE, INVISIBILITY | Player abilities cut off during a Boss fight |
Health.Prevent_Regeneration | false | Stop all Bosses regenerating health from any source |
Skills.Target_Range | 8 | How close a player must be for a targeting skill to fire |
Variables.Nearby_Boss_Radius | 20 | How far the %boss_*% placeholders look for a Boss |
Prevent_Vanilla_Mobs.Enabled | false | Block vanilla mob spawning entirely, per world and per entity |
Timezone | "" | Timezone for the real-life clock in spawn rules. Empty uses the server's own |
Sort_By_Type | false | Group the Bosses menu by mob type instead of A-Z |
Register_Regions | true | Boss regions and the /boss region command. Restart after changing |
Register_Tools | true | The tools from /boss tools. Restart after changing |
Debug | [] | Print diagnostics. Sections: spawning, skills, region-keep, unloaded, commands, health |
Boss Bar and Health Bar live under Fighting, see Customizing Bosses.