Its Cross's Mobs Below

Mobs Below disables the natural spawning of hostile mobs above a configurable Y-level, making the surface and other high-altitude areas safer while preserving underground exploration and danger.

By default, hostile mobs will only naturally spawn at Y=60 or below, but this limit can be changed in the config file to fit your world or modpack. Peaceful mobs and spawner-generated mobs are unaffected.

This mod is ideal for players who want a more relaxed overworld experience without removing hostile mobs entirely. Nights become less punishing on the surface, allowing you to build, explore mountains, or travel above the configured height without constant attacks, while caves, mines, and the deep underground remain dangerous and rewarding to explore.

Features:

• Disables natural hostile mob spawning above a configurable Y-level.
• Default spawn limit is Y=60.
• Fully configurable through the mod's config file.
• Compatible with vanilla and modded hostile mobs that use natural spawning.
• Leaves mob spawners, commands, and peaceful mob spawning unchanged.