The pitch

Vanilla has three bosses. You've beaten all of them.

FIW Bosses hands you the toolkit Mojang didn't: drop a JSON file into config/fiw_bosses/bosses/, run /boss reload, and a fully custom encounter is live on your world — changing tactics as its health drops, summoning minions, taunting your players, and dropping exactly the loot you decide.

It isn't one hardcoded boss bolted onto the game. It's a framework: HP-threshold phases, per-phase ability loadouts, custom minions with their own AI, pre-fight and pre-death dialogue, custom skins, hot reload — one config schema that behaves the same on every loader and version it supports.

🧩 Both-sides mod. Install the matching jar on the server and every client that joins it.

Sixty seconds to your first boss

config/fiw_bosses/bosses/storm_caller.json

{
  "id": "storm_caller",
  "displayName": "&b&lStorm Caller",
  "health": 500,
  "speed": 0.28,
  "phases": [
    {
      "hpThresholdPercent": 1.0,
      "abilities": [
        { "type": "chain_lightning", "cooldownTicks": 120, "params": { "bounces": 5, "damage": 10 } },
        { "type": "beam", "cooldownTicks": 180, "params": { "damage": 4 } }
      ]
    }
  ]
}

/boss reload
/boss spawn storm_caller

That's the whole loop. Tweak the file, reload, fight again — no restart, ever.

What you can build

🔥 Phase-based fights — every boss can rewrite its own rules as it bleeds. Each phase changes speed, damage, equipment, the minion pool, transition messages, sounds, particles, and its entire ability set.

🧠 Eight movement styles — hit_and_run, guard_point, phase_walk, hover, sniper, berserk, plus classic strafing or plain vanilla pathing. Your sniper kites; your berserker hunts.

👥 Custom minions — true FIW minions with skins, gear, abilities, AI modes and loot, or plain vanilla mobs for quick summons. Minions can escort the boss, hold a position, or fight on their own.

🎭 Disguises — keep full FIW logic but render a boss or minion as any vanilla or modded mob with renderEntity, or use a real player skin. Your "zombie" can cast meteors.

💬 Fight flow & dialogue — start a boss dormant and invulnerable until a player right-clicks it; play pre-fight lines, then begin. Hold it at 1 HP for last words before it falls. Every chat message is optional — silent bosses are one omitted param away.

🛡️ Damage protection — per-boss, per-phase, and per-minion damage multipliers keyed by weapon item, damage type, or category. Tame the overpowered mace/spear ("minecraft:mace": 0.2), resist potions ("magic": 0.3), or grant true immunities ("fall": 0) — made for servers with custom weapons.

⚔️ Factions — allied bosses and minions never turn on each other and their AoE can't hurt allies, with per-entity switches (damageFactionAllies, targetFactionAllies, damageOwnGroup) when you want infighting.

🌊 Water & lava handling — no more river cheese: bosses can chase players into water (canSwim), never drown, sink and fight underwater (floats: false), swim faster, ignore currents, and shrug off lava (fireImmune).

🎲 Loot ranges — roll random drop amounts with minCount/maxCount (10–120 diamonds at 50% chance); big rolls split into stacks automatically.

♻️ Hot reload & persistence — /boss reload re-reads everything live, deleted configs are removed from the world, and a boss's phase survives server restarts.

50+ abilities, mixed and matched

Abilities are small, tunable attack modules. Stack them on a phase, set cooldowns, tune the params, and a moveset is born.

…and dozens more — slams, beams, meteors, orbital strikes, tornadoes, sonic booms, judgment marks, divine executions, summons, heals, shields, and ultimates. The full list and every parameter live in the documentation.

Supported versions

Fabric builds need Fabric API. One boss file behaves the same on all eight targets.

Optional: Fiw Custom Items — when present, equipment and loot can reference its items by toolId; when absent, those entries are skipped and nothing breaks.

Commands

/boss needs op level 2; /boss reload needs op level 3.

/boss spawn <id> [x y z] [count]   /boss list        /boss kill <id> | all
/boss minion spawn <id> [count]    /boss minion list /boss minion kill <id> | all
/boss reload