Monster Spawner

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 the mob that is spawned, though it does not give off any light. The model inside the spawner rotates faster until the next mob is spawned.



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 and the light level within the spawning radius remains below seven. The player must be within 16 blocks for spawners to generate mobs, which will spawn 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. Here is a guide for dungeon mob farming.

Unedited Monster Spawners will spawn Spiders, Skeletons, or Zombies. Spawners do not drop resources when destroyed, though in Beta they can be obtained through the /give operator command. A placed spawner will spawn only pigs. The spawner type can be changed through Hacking.

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

 * Monster spawners are more quickly broken with a pickaxe, but they will not drop any resource-blocks. There is no way to legitimately get a monster spawner to place where you want.
 * If you are within a 16 block radius, the monster spawner will activate. If you are not within range, the doll inside the spawner will stop spinning and deactivate.
 * The monster spawner will wait 200 + x ticks between spawns where x is a random number selected between 0 and 599 on each spawn, and a tick is 1/20 of a second. This means that on average, it will attempt to spawn a mob every 24.975 seconds. It tries 4 times to place the mob at a random position in an 9 x 9 x 9 area, and gives up on placing that mob if it cannot find a valid position after the 4 attempts. It will not attempt to spawn a mob if there are already 6 or more monsters of the specified type inside the box.
 * When killed, a zombie will drop 0, 1, or 2 feathers, for an average of 1 feather/zombie. This means that the ideal production rate of a zombie spawner trap is (60 seconds/minute) / (24.975 seconds/zombie) * (1 feather/zombie) = 800/333 feathers/minute ~= 2.40 feathers/minute. Analogously, ideal spider traps will produce 2.40 strings/minute, and ideal skeleton traps will produce both 2.40 bones/minute and 2.40 arrows/minute. At this rate, the expected time for a stack of 64 items is 26 minutes and 38 seconds.
 * 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.
 * When mining near a monster spawner that has no valid places to spawn sometimes a monster will spawn immediately after a block is mined. The player should take caution for this reason while collecting Moss Stone from a dungeon but hasn't destroyed the monster spawner.  It's speculated this might happen because the spawner gets a chance to spawn before the lighting calculation for the space the block occupied.
 * If a spawner is edited to create Ghasts or Giants(Giants and slimes don't spawn), the model inside will be miniaturized, but not enough to fit the cage properly, because the scaling factor used is the same as with other mobs, though ghasts and giants are a lot bigger.
 * 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(maximum to four) 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. (Fast machines cannot do this)
 * 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).
 * The miniature mob model displayed inside the monster spawner was enabled again in Beta 1.2 after missing for several versions.
 * There is currently a bug in multiplayer in which all monster spawners show a pig model inside, despite what it actually spawns.
 * Monster spawners can spawn monsters in a nearby cave, even when the monster spawner is fully lit.
 * As of Beta 1.3, on multiplayer, there is a bug where pigs can spawn near spawners if there is grass. These pigs are client-side and can never be killed.
 * As of Beta 1.4, on multiplayer, there is a bug where a surface dungeon's spawner will be a pig spawner.
 * As of Beta 1.4, on multiplayer, there is a bug where mob spawners are extremely rarely found inside of dungeon chests.
 * The model inside the monster spawner has an ID number like all other mobs, though it is only visible at certain angles.
 * If you press F3 you can find a dungeon more easily since mob spawners now have an entry ID number