Boss Arena adds biome-aware, auto-generated battle arenas that spawn customizable mobs defined via simple JSON configs.
Description
Boss Arena generates compact, natural-looking arenas as you explore. Each arena can spawn specific mobs (vanilla or from other mods) defined by simple JSON files—no coding required.
How it works
On world load, the mod looks for JSON specs in config/bossarena/evergaol_specs/.
When terrain generates in a matching biome, an arena template is placed two blocks sunk into the ground, with gentle backfill so it blends with the terrain.
A trigger inside registers the arena and handles mob spawning defined by the JSON.
Quick Start (uses the built-in default)
Launch the game once with the mod installed.
It creates: config/bossarena/evergaol_specs/arena_01.json.
Play or create a world and explore the target biome—arenas will appear naturally.
Default example:
arena_01.json – Plains arena with Husks:
Add your own Arena
Create arena_02.json in the same folder:
JSON fields
biomes / biome_tags: Where arenas can generate (IDs or tags like #minecraft:is_savanna).
weight: How often this arena is picked (higher = more frequent).
support_blocks: Blocks (or tags) used to fill/terrace the base so the arena looks natural
spawn: Which mob appears, how many (count), how spread out, and small position offsets.
Tips
Want more arenas? Copy a JSON, change the id, biome(s), and spawn.
For broad coverage, prefer biome_tags over listing many biomes.
If edges look odd, add local ground blocks to support_blocks (or use a tag).
Find correct mob IDs with /summon: type /summon in-game and use autocomplete to browse entities installed in your pack.
The value you see is the exact namespace:entity_id to put in spawn.mobId (e.g., alexscaves:tremorsaurus from the second example).
You can do the same with modded biomes: use /locate biome <modid:biome_name> to get the biome ID from the mod, then use that ID in your biome(s) list or match it via biome_tags.
Compatibility
Compatible with vanilla and modded mobs.
Designed to be lightweight; arenas generate as you explore.
Troubleshooting