In Control — Vanilla Natural Spawn Tuning
Minecraft 1.20.1 Forge

What this changes
- Denies 20% of natural spawn attempts for the listed vanilla hostile mobs.
- Denies 35% of natural creeper spawn attempts.
- Creepers are in their own rule, so they receive the 35% setting rather than both reductions.
- Only vanilla mobs listed in spawn.json are affected. Modded horror entities are not listed.
- The rules are not dimension-restricted, so they apply in any dimension where these vanilla entities naturally spawn.
- No global mob-count cap is used. Existing mobs in caves do not fill a shared cap and stop surface spawns.
- Difficulty is unchanged.

Scope
The rule uses spawntype = natural, so it targets natural spawn attempts. It does not intentionally reduce mobs produced by ordinary mob spawners, spawn eggs, commands, or other non-natural spawn reasons.

Tuning
- Change random: 0.20 to 0.10 for 10% fewer natural spawn attempts, or 0.25 for 25%.
- Change the creeper random value 0.35 to 0.25 for a lighter reduction or 0.40 for a stronger one.
- A random value is the chance that the rule denies an eligible spawn attempt, not a hard cap on the number of mobs.

Restore default behavior
Replace spawn.json with [] and run /incontrol reload or restart.

Official documentation
https://mcjty.eu/docs/mods/control-mods/control-mods-20
https://mcjty.eu/docs/mods/control-mods/control-mods-20-table
