Monster Spawners are blocks with a transparent blue lattice structure found in dungeons as a guardian to the treasure found within. Inside the block there are flames and a miniature spinning version of mob that is spawned, though it does not give off any light. A spawner has a range of four blocks and it will create mobs at the same vertical height as the spawner provided there is space for its mob type to be generated. The player must be within 16 blocks for spawners to generate mobs and they will keep spawning mobs even if light is raised above the normal maximum spawning level (daylight being the exception) and even if there is a wall between the spawner and an available spawning space inside the four block radius. This has led to many contraptions designed to kill whatever drops from it, usually a drowning trap, allowing the player to collect spoils in great numbers with little risk.
Spawners cannot be prevented from spawning monsters by surrounding the spawner with torches.
Monster Spawners will either spawn Spiders, Skeletons, or Zombies. Spawners cannot be picked up by the player when destroyed, though they could be back in Infdev and in Beta they can be obtained through the ops /give command, placing a spawner will make it spawn only pigs.
In Peaceful difficulty, Monster Spawner blocks will still appear, but any spawned mobs will disappear the instant they spawn. This makes it easy to make the aforementioned trap without any trouble.
Trivia
- In cases where the dungeon is located near the surface, the player can remove the ceiling of the dungeon and expose the Monster Spawner and surrounding area to direct sunlight, preventing monster spawns during the day [1].
- When mining near a monster spawner that has no valid places to spawn sometimes a monster will spawn immediately after a block is mined. This could be because the spawner gets a chance to spawn before the lighting calculation for the space the block occupied.
- There is a bug that comes up rarely where a monster spawner "spawns" and there is no visible enemy, though sounds can be heard and when you move closer the mob sometimes appears.
- Occasionally, a monster spawner may spawn two monsters at once. It is likely that another monster will spawn sooner than normal if this occurs.
- If the "F" key is rapidly pressed, everything in the map will become invisible except fire (such as the fire inside a monster spawner). This can make finding dungeons easy.
- When hacked into the inventory (Or in Infdev), they only spawn pigs when placed. These player placed spawners will only create pigs if there is grass with a light level above 9.
- Monster spawners can be edited with a map editor or client mod to spawn any mob (Slimes have certain conditions that must be met to spawn).
- In Beta 1.2, the mob being spawned will be displayed inside the monster spawner.
A mob spawner with a spider inside. Beta 1.2