
Fiw Bosses
A data-driven custom boss framework for NeoForge or Fabric Define multi-phase bosses and minions with configurable abilities entirely through JSON no coding, no restarts.
About this Mod
FIW Bosses
A data-driven custom boss framework for NeoForge 1.21.1, Fabric 1.21.11, and Fabric 1.20.1 — inspired by MythicMobs, built from scratch.
Define fully custom multi-phase bosses entirely through JSON files. No coding, no server restarts — drop a config, reload, and your boss is live.
Why FIW Bosses?
Neither Fabric nor NeoForge has a good lightweight boss framework. MythicMobs is Bukkit/Spigot only. FIW Bosses fills that gap — fully JSON-driven so anyone can create bosses without touching code. It installs on both the server and the client: this is not a server-side-only mod, so every player needs it installed.
Supported Loaders
| Loader | Minecraft | Status |
|---|---|---|
| Fabric | 1.21.11 | Active — main version · the only build with FIW Tools integration |
| NeoForge | 1.21.1 | Active |
| Fabric | 1.20.1 | Legacy — may still receive occasional updates, but not guaranteed |
All three ports share the same JSON schema, same 42 abilities, same minion system, same commands. A boss config written for one works on every other — drop the same file into NeoForge or either Fabric branch and it behaves identically.
Features
- JSON-driven bosses — create any boss without writing a single line of code
- Multi-phase system — HP thresholds trigger phase transitions with new abilities, speeds, equipment, sounds, and particle effects
- 42 configurable abilities — melee, ranged, mobility, AoE, crowd-control, utility, and ultimates
- Custom minion system — define custom minions via JSON with their own stats, skins, equipment, abilities, loot, and AI modes (normal, follow boss, static) — or use vanilla mobs with stat overrides
- Pre-fight activation — boss starts passive and immortal; right-click to trigger dialogue and start the fight
- Pre-death dialogue — boss held at 1 HP on the lethal hit, speaks final words, then dies
- Custom skins — use any player's skin or load a local PNG file (bosses and minions)
- Custom equipment — full item and NBT support per slot, swappable per phase
- Dynamic aggro — aggro switching, revenge targeting, multiplayer-friendly
- Strafing AI — bosses circle and strafe at close range
- Custom loot tables — per-item drop chances with full NBT support (bosses and minions)
- Hot reload — reload all boss and minion configs without restarting the server
- Phase persistence — boss phase survives server restarts
- FIW Tools integration (Fabric 1.21.11 only) — bosses equip and drop custom FIW Tools items by id; optional, and degrades silently when FIW Tools isn't installed
Quick Start
- Drop the correct JAR into your mods folder — on the server and on every player's client (this mod is not server-side only)
- Start the server — the config folders generate automatically under
config/fiw_bosses/ - Copy an example boss into the bosses folder
- Reload configs in-game
- Spawn your boss
In-game commands let you spawn, list, kill, and reload bosses and custom minions on the fly — full reference on GitHub.
Minion System
Custom minions sit alongside bosses in the config folder — each one a JSON file with its own stats, skin, equipment, abilities from the 42-ability pool, loot drops, and AI behavior. Bosses summon them by ID through the summon-minions ability, or you can spawn one directly via command.
Cross-Version Parity
Every config written for any version of the mod works on every other version, byte-for-byte. The Fabric 1.21.11 port handles Minecraft's newer DataComponents API behind the scenes — your JSON keeps using the same enchantments, display names, custom model data, and attribute modifiers it always did, and they take effect identically on every loader.
FIW Tools Integration (Fabric 1.21.11 only)
Paired with FIW Tools, bosses can wield and drop fully custom items. In any boss or minion config, an equipment slot or loot entry can take a toolId instead of a vanilla item — the boss then equips or drops that FIW Tools item, with its abilities, enchantments, attributes, curses, and imbuements intact. The lookup is optional: without FIW Tools installed the reference is simply skipped and nothing breaks. This integration currently exists only on the Fabric 1.21.11 build.
Requirements
NeoForge 1.21.1 (active)
| Minecraft | 1.21.1 |
| NeoForge | 21.1.x |
| Java | 21 |
| Client-side required | Yes (not server-side only) |
Fabric 1.21.11 (active)
| Minecraft | 1.21.11 |
| Fabric Loader | 0.18.1 or newer |
| Fabric API | 0.141.3+1.21.11 or newer |
| Java | 21 |
| Client-side required | Yes (not server-side only) |
Fabric 1.20.1 (legacy)
| Minecraft | 1.20.1 |
| Fabric Loader | 0.18.3 or newer |
| Fabric API | 0.92.2+1.20.1 |
| Java | 21 |
| Client-side required | Yes (not server-side only) |
Documentation
Full configuration reference with all fields, ability parameters, and examples available on the GitHub repository.
License
GNU General Public License v3.0
Made by Fi3w0 — built for a private SMP, shared with everyone.
Developed with assistance from Claude Opus 4.8.
Available Versions
How to Install Fiw Bosses on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.11).
Install Mod
Open the mod browser in the dashboard and search for "Fiw Bosses". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.11, 1.21.1, 1.20.1
Server-side
✓ RequiredRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
Fiw Bosses server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.21.11). You can switch loaders with one click in the panel.
Is Fiw Bosses compatible with fabric and neoforge?
Fiw Bosses officially supports fabric, neoforge for Minecraft 1.21.11, 1.21.1, 1.20.1. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with Fiw Bosses – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Fiw Bosses consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
Similar Mods
Rent Modded Server
Install Fiw Bosses with just one click on your server.