Mobs Love Darkness

A Fabric mod for Minecraft 1.21.11 that gives certain mobs a chance to fixate on and destroy nearby light sources, creating dangerous dark zones and rewarding players who pay attention.

What it does

Some mobs will occasionally lock onto nearby torches, lanterns, and campfires and attempt to destroy them. A fixated mob glows and emits soul fire particles, giving an observant player a chance to react before their lighting is gone. Once the mob reaches the light source it breaks it, playing a distinctive sound and returning to normal behavior in the newly created darkness.

Phantoms may occasionally destroy exposed torches during their swooping attacks, making open-air lighting somewhat vulnerable at night — but their erratic flight means covered lighting remains relatively safe.

Everything is highly configurable.

Features

Configurable list of eligible mob types — any mob can be added via config
Configurable list of targetable blocks — works with any block ID including modded blocks
Per-mob-type goal assignment chance — phantoms can be tuned separately from high-spawn mobs like zombies
Optional glowing effect on fixated mobs for player readability
Optional soul fire particle trail while fixating
Optional distinctive sounds on fixation start and light source destruction
Unreachable targets are blacklisted per-mob to prevent stuck behavior
Block protection mod compatible — protected blocks are detected and blacklisted gracefully
All behavior is server-side only, no client installation required for multiplayer

Default behavior

By default, the following mobs are eligible for the light fixation goal:

Mob	Default eligibility chance
Zombie	5%
Husk	5%
Zombie Villager	5%
Zombified Piglin	5%
Phantom	75%

The following blocks are targeted by default:

Torch / Wall Torch
Lantern
Soul Torch / Soul Lantern
Campfire / Soul Campfire

Configuration

The config file is generated at config/mobs-love-darkness.json5 on first launch. All fields include descriptions and valid ranges directly in the file.

Config	Default	Description
`LightSourceSearchRadius`	16	Block radius to search for light sources. Range: 1–128
`LightSourceSearchRadiusVertical`	4	Vertical block radius to search for light sources. Range: 1–128
`LightSourceBreakTimeTicks`	20	Ticks to break a light source (20 ticks = 1 second). Range: 1–1200
`LightFixationChance`	0.05	Chance per second that an eligible mob fixates on a nearby light source. Range: 0.0–1.0
`LightFixationSpeedMultiplier`	0.85	Movement speed multiplier while fixating (1.0 = normal speed). Range: 0.1–10.0
`LightFixationCooldownTicks`	200	Ticks before a mob can fixate again after destroying a light source. Range: 0–72000
`LightFixationMaxGoalTicks`	600	Maximum ticks spent on a single fixation attempt before giving up. Range: 100–72000
`LightFixationGoalPriority`	3	Goal priority (lower = higher priority, vanilla zombie attack = 2). Range: 1–10
`EnableParticles`	true	Soul fire particle trail on fixated mobs
`EnableSounds`	true	Sounds on fixation start and light source destruction
`EnableLightFixationGlowEffect`	true	Glowing outline on fixated mobs
`TargetableLightSources`	see above	List of block IDs to target, including modded blocks
`LightFixationEligibilityChancePerMobType`	see above	Per-mob-type chance to receive the goal on spawn

Performance guidance

Search cost scales cubically with radius — a radius of 128 checks ~500x more blocks than a radius of 16. Balance search radius against mob eligibility:

Search radius	Recommended max eligible mobs
16 (default)	~50
32	~20
64	~5
128	~1-2

LightSourceSearchRadiusVertical (default: 4) also contributes to search cost. Increasing it significantly will reduce performance — keep it low unless your use case specifically requires searching underground.

These are rough guidelines. Actual impact depends on hardware and other mods.

Adding modded mobs and blocks

Any valid block or entity registry ID works in the config lists:

"LightFixationEligibilityChancePerMobType": {
    "minecraft:zombie": 0.05,
    "minecraft:phantom": 0.75,
    "alexsmobs:warped_mosco": 0.10
},
"TargetableLightSources": [
    "minecraft:torch",
    "minecraft:wall_torch",
    "supplementaries:oil_lamp"
]

Compatibility

Game rules

This mod respects the mobGriefing game rule. If mobGriefing is disabled when a mob spawns, it will not receive the light fixation goal. Mobs that already have the goal when mobGriefing is disabled will stand down gracefully without breaking blocks.

Works with:

Sodium, Iris, Lithium, and other performance mods
Mods that add new mob types — add them via config
Mods that add new light source blocks — add them via config

Does not affect:

Client-side dynamic lights from shader mods — only actual world blocks are targeted
Bedrock Edition — Java only

Potential conflicts:

Mods that completely replace mob AI goal selectors may prevent the goal from being injected
If goal priority conflicts with another mod, adjust LightFixationGoalPriority in config (vanilla zombie attack goal is priority 2)

Block protection mods (GriefPrevention, FTB Chunks, etc.) — protected blocks are detected after a break attempt and blacklisted, preventing repeated attempts. Note: FTB Chunks mob griefing protection on Fabric only covers Endermen by default and will not prevent this mod's block breaking — use the mobGriefing game rule for global protection instead.

Known limitations

There is no distinction between player-placed and world-generated blocks — blocks that are naturally generated can also be targeted
Phantoms have imprecise torch-targeting due to their flight navigation — this is somewhat by design, as accurate phantom targeting would be difficult to counter
Disabling the mobGriefing game rule prevents new mobs from receiving the goal and prevents blocks from being broken by mobs that already have it

GitHub

https://github.com/AndartaMC/mobs-love-darkness

License

MIT — feel free to include this mod in modpacks.