Boss Arena

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

No arenas? Check you’re in a matching biome and that your JSON is valid (IDs and commas).

Mob not spawning? Verify the correct namespace:mob_id from the other mod.

Have fun turning your world into a tour of curated boss/mob fights—on your terms!

Special thanks to:  pistonpoek for the awesome arena
and 

themodderg  for the new logo