When your monster spawner gives nothing
A silent spawner almost always has one of these reasons behind it. Check them in order.
Why your spawner gives nothing
It is the most asked question on the server.
First, it only runs if a player is standing less than 16 blocks away. Nobody nearby, nothing comes out.
Then light: animals, cows, pigs and sheep, want grass and brightness, from light level 9 up. Monsters want complete darkness, level 0: a single torch next to it is enough to stop everything.
Then room: the spawner looks for free ground in a box roughly 9 blocks wide, 9 deep and 3 high, with itself in the middle. If everything is blocked up, nothing appears.
When the three conditions are met, the spawner puts out 1 to 4 mobs every 10 to 40 seconds. On average that comes to 350 mobs per hour per spawner, and double that with a Spawner Booster.
The classic trap: your spawner blocks itself
A spawner stops producing if there are already 6 mobs of the same species around it. That is what kills most farms elsewhere.
Here, a stack counts as a single mob. A stack of 2,000 monsters sitting under your spawner does not block it, and you do not even have to clear it out. That is what makes big farms possible on this server.
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