Java Edition 15w38a

15w38a is the twenty-fourth snapshot released for 1.9. Notably, this update added skeleton horsemen to the game.

Mobs

 * Skeleton Trap Revision 1.png Skeleton Horsemen
 * Added "skeleton trap" horses. When a player approaches to within 10 blocks, the following will happen:
 * The  flag is cleared.
 * Lightning strikes the horse.
 * The horse will become skeletal if it isn't already.
 * The horse becomes tame.
 * The horse becomes fully grown (if a baby) and the breeding cooldown is reset.
 * A skeleton is spawned riding the horse.
 * If on peaceful, the Skeleton will not spawn, while the Horse will.
 * The skeleton has damage immunity for 3 seconds.
 * The skeleton will not despawn since they have the tag  set to true.
 * The skeleton will be wearing an iron helmet, unless it randomly spawned with some other headgear.
 * The skeleton's bow and helmet will be enchanted as if on an enchantment table at level 5–22.
 * The level is higher depending on regional difficulty; on Easy it will always be a level-5 enchantment.
 * Three additional skeletal horses with riders will be spawned in the vicinity.

Command format

 * NBT tags:
 * (byte): Indicates whether the horse is a skeleton trap (i.e. whether or not the horse will spawn 4 undead horsemen in its place when a player gets within 10 blocks of it).
 * (integer), incremented each tick when  is set to 1. The mob automatically de-spawns when it reaches 18000 (15 minutes). This will prevent the hostile horses from overflowing the world, similar to chicken jockeys.
 * (integer), incremented each tick when  is set to 1. The mob automatically de-spawns when it reaches 18000 (15 minutes). This will prevent the hostile horses from overflowing the world, similar to chicken jockeys.


 * Statistics
 * Added "Times Slept in a Bed" to track the amount of times a player has used a bed.

Blocks

 * Crops
 * Improved drop chances for seeds (average $1 5/7$ per crop harvested instead of $1 3/5$), potatoes and carrots (average $2 5/7$ per crop harvested instead of $2 3/5$), and beetroot seeds (average 2 per crop harvested instead of $4/5$).


 * End rod
 * The player can no longer step up onto an end rod as if it were a slab.


 * Fire
 * Fire goes out less often under the rain.
 * The chance of going out each fire tick is reduced from 100% to 0–45%, depending on the  property.

Mobs

 * General
 * Improvements to mob AI.


 * Skeletons
 * Have new idle sounds.
 * Skeletons can now walk, strafe and shoot at the same time.
 * They walk away from players that are too close and towards players that are too far.
 * They will also sprint towards the player when very far away.
 * Now can spawn riding "skeletal horses" through the new "skeleton trap" horse.


 * Tamed Ocelots & Wolves
 * Deaths (and killers) are now announced to their owners on chat, even if unnamed.


 * Villagers
 * Will now pick up and plant beetroot seeds.
 * Will now pick up beetroot and use it in the same way as they do carrots and potatoes.

Non-mob entities

 * Lightning
 * Natural lightning strikes may spawn a "skeleton trap" style skeletal horses.
 * Chance is calculated from the regional difficulty score: 5% * raw regional difficulty score.
 * 3.75–7.5% chance on Easy, 7.5–20% chance on Normal, 11.25–33.75% chance on Hard.

Video
Video made by slicedlime:

Trivia

 * 15w38a was previously removed from the launcher for some time, but was added back in September 2018.