Can Mobs Spawn on Rails in Minecraft?
No, mobs cannot spawn directly on top of rails and rail components like powered rails, detector rails, and activator rails as of Minecraft 1.4.2. This allows minecart travel across rails to be relatively safe from mob interference.
However, parts of a mob‘s body may still hang into the rail space, potentially stopping or reversing a player‘s minecart. So tunnels should still be lit and walled off.
Mob Spawning Spheres
Hostile mobs can only spawn within 128 block radii spheres centered on each player in the world. The mob capacity per sphere varies by difficulty:
| Difficulty | Hostile Mob Cap |
|---|---|
| Easy | 16 |
| Normal | 32 |
| Hard | 64 |
So on hard difficulty with 5 players, there could be up to 320 hostile mobs active around them at once!
Passive mobs have a more limited range, spawning within 32 blocks horizontally and 16 blocks vertically of players.
Despawning Mechanics
Mobs that move farther than 128 blocks from the nearest players will instantly despawn. So the natural mob population is essentially limited to those spherical ranges.
Players can use this despawn behavior to their advantage in farms…
Efficient EXP Farm Design
By funneling mobs over 128 blocks away through portals or minecarts before killing them, a player can harvest XP extremely quickly. The game will rapidly spawn more mobs to try to maintain the cap.
For example, sending mobs 500 blocks away before bringing them back to a killing chamber can yield over 1,000 XP per hour at max rates.
Iron Golem Farming
Iron golem farms built in spawnable spaces within 16 blocks of villager beds can produce iron at astonishing rates through snowballing population growth.
Each village can spawn one golem approximately every 10 minutes if the caps are maintained. A simple 20 village stack farm can generate over 13,000 iron ingots per hour with enough player-created villager houses.
Guardian Farming
By clearing all water spaces within 128 block radii spheres centered around the player in ocean monument wings, guardians will spawn extremely quickly within the monument itself.
Guardians spawn up to 24 per cycle in monument wings. With water jets flushing them to a central killing chamber, rates over 5000 drops per hour are possible with Eff V!
Slime Chunk Farming
Slimes spawn below layer 40 in only specific chunks based on the world seed. Luckily there are online tools to map all slime chunks in a world download.
In slime chunks, 1-4 slimes will spawn in every 8x8x3 space below Y-40 that players create. This can yield over 2000 slimeballs per hour with enough spawnproof platforms at say Y-15.
Spiders vs Creepers
Spiders and creepers actually compete to spawn in the dark spaces of caves and the surface. Spiders get heavily prioritized, with creepers only spawning ~15% as often.
So clearing a giant hollow space that’s totally dark will be filled almost entirely with spiders and cave spiders, which can make for easy string farming!
…
And that‘s just a glimpse into advanced mob mechanics and how to leverage them! Let me know if you have any other questions. Happy crafting!
