Wither Skeleton

Wither Skeletons are dangerous hostile mobs that spawn in Nether Fortresses. Wither Skeletons are the Nether equivalent of skeletons. Unlike skeletons, Wither Skeletons use stone swords and are three blocks tall and immune to fire. When hit by a Wither Skeleton on any difficulty, the player is inflicted with the "Wither" effect for 10 seconds, darkening the health bar and further damaging the player. When killed, the mob may drop coal and bones, and very rarely drop their skull and the stone sword. They have a 1/40th chance of dropping either of these items. This chance will go up if you use a sword with a Looting enchantment. The skulls are the key items to creating the Wither boss.

Wither Skeletons, like all Nether mobs, are immune to fire and lava and are not damaged by daylight. Some Wither Skeletons can also pick up items, weapons, tools, and armor, similar to other undead-type monsters.

Appearance
The wither skeleton has black bones instead of light gray bones. They carry a sword instead of a bow and have smaller mouths than regular skeletons they also have a skull that looks like a wither and can rarely drop them.

Spawning
Wither Skeletons will only spawn naturally in a nether fortress (even if the area where a fortress would be was generated before their inclusion, since it is tied to the location of the fortress, not the fortress itself). Block type does not matter with naturally spawned Wither Skeletons (e.g., replacing a Nether Fortress' bricks with normal blocks will still allow wither skeletons to spawn); they follow the same spawning conditions as naturally spawning Skeletons: light level 7 or less where their lower half will be.

When used in the Nether, Skeleton spawn eggs are able to spawn Wither Skeletons instead of the normal skeletons 80% of the time. Similarly, when a spider is spawned in the Nether (whether via spawn egg or a mob spawner), it has a 0.8% chance of spawning with a wither skeleton jockey instead of an ordinary spider. Not all Wither Skeleton Jockeys are Wither Skeletons, though.

Wither Skeletons in Overworld
There are ways to have wither skeletons in the overworld. One way is to have a Nether portal in where the mob is to the overworld. Another way is to use inventory editors. Try spawning the wither skeleton by using the skeleton spawn egg in nether.

Wither Skeletons can also be spawned in the overworld using /summon or custom spawners.

Combat
Wither Skeletons are tough mobs to fight due to their high attack strength ( on normal), their ability to inflict the Wither effect, their ability to move faster than other mobs, and the probability of them being near a Blaze. Their biggest weakness is that they cannot pass through a two block high passage because of their height, much like Endermen.

If there are lots of Wither Skeletons and Blazes around, bring some Blocks of Iron and a pumpkin to make an Iron Golem. This is also a good way to farm the drops of the Wither Skeleton.

If an Iron Golem is not an option it is advised that the player treat the Wither skeleton as they would a Zombie, albeit with far more care. If you attack and move backwards at the same time you should not have any trouble avoiding damage provided you have some room to maneuver. If you have your back to a wall spam attacking should be enough to kill a single Wither Skeleton without taking damage. If you have your back to a wall and are facing more than one Wither Skeleton it is strongly advised that you move to a position where you have room to maneuver as the Wither Skeletons move slightly faster than zombies and so more easily overwhelm you. Sniping with a bow is also effective although it is not recommended at under 10 blocks away (without a punch enchantment) as Wither Skeletons move surprisingly fast.

If you find yourself facing a Blaze at the same time the best course of action is to move into a place inaccessible for the blaze -such as a corridor- and then proceed in taking the above steps to kill the Wither Skeleton. If this is not possible it is suggested that the player run out of range of the blaze and turn to face the Wither skeleton. It is strongly advised that inexperienced players do not face both mobs at the same time as this often leads to death, but for more experienced players willing to face both you should either; deal with the blaze first by charging at it with a sword (do not use a bow as you will be exposed to attack) and then turning and facing the Wither Skeleton or (more recommended) putting the Wither Skeleton between yourself and the Blaze so as to use its body as a shield against the Blaze's fireball attack, and then charging the Blaze once it is dead.

Like all mobs, Wither Skeletons can travel through a Nether Portal. This means that if you put a Nether Portal inside the Nether Fortress, and maneuver yourself so that the portal is between you and the Wither Skeleton (or any other hostile mob), the Wither Skeleton will travel towards you but teleport into the overworld.

Invisibility potions will allow you to fight a Wither Skeleton with ease.

You can also build partial walls in a nether fortress that fall down from the ceiling and leave a walkway two blocks high. Wither skeletons can't move through two block high spaces so building such structures limits their mobility, and will allow you to damage them with impunity.

If a wither skeleton is able to acquire a bow, it will use it to shoot at you. Any arrows it shoots will be on fire, and will cause you to catch fire, regardless of the bow's enchantments. It is not recommended to allow a wither skeleton access to a bow.

Depending on your display settings, it may be possible to see your hearts' edges showing you the amount of HP left when suffering the wither effect.

Bugs

 * Because of their shared entity ID with skeletons, their behavior is similar, such as their hitboxes are the same as skeletons, along with other characteristics like heading away from sunlight despite the fact that they cannot catch fire. Also, the Wither Spider Jockey is a glitch, because of their behavior, and only exist in Creative mode through spawn eggs.
 * Rarely, when the Wither Skeleton is pushed in a minecart into the lava, it will float in the air, seeming to "jump" in there. The glitch will cause the skeleton to disappear within a minute.
 * Because Wither Skeletons have the same entity ID as skeletons, they sometimes spawn in two-block-high spaces of Nether forts that are too short for them, causing them to suffocate.

Trivia

 * The drop rate for the wither skeleton skull is 1/40 (2.5%).
 * A normal skeleton will spawn in a Nether Fortress instead of a Wither Skeleton 20% of the time.
 * Wither Skeletons wield stone swords, yet there is no natural stone in the Nether.
 * Their drop of coal makes it possible to craft fire charges without leaving the Nether.
 * This also means that coal is a renewable resource.
 * Wither skeletons could be seen as to skeletons as cave spiders are to regular spiders, because they both are a mob-variant and have a special player-damaging after-effect. However, unlike cave spiders, they have weaknesses compared to skeletons.
 * It is a common misconception that the Wither effect gives Wither Skeletons health back when it actually only damages the player.
 * Wither skeletons, as with zombies, zombie pigmen, and regular skeletons, will sometimes wear pumpkins on Halloween (October 31st).
 * If a wither skeleton is wielding a bow, it will use it like an ordinary skeleton, but the arrows it shoots will be set on fire. This happens whether or not the bow has the Flame enchantment.
 * Wither Skeletons burn in the sun, but don't die, due to being a nether mob and thus having immunity to fire, similar to Zombie Pigmen.
 * Wither Skeletons are also immune to damage from lightning, again due to their immunity to fire.
 * Wither Skeletons are one of the three mobs that carry a weapon by default, the other two being the Skeleton and the Zombie Pigman.
 * Ironically, Wither Skeletons aren't immune to the Wither effect.
 * Wither skeletons are among the only 6 mobs not having spawn eggs (the others being the Iron Golem, Snow Golem, Wither, Giant and the Ender Dragon), due to their shared ID with normal skeletons.
 * Wither skeletons are one of the four mobs that give a debuff to the player. The other three being the Wither, the Cave spider and the Witch.
 * It is possible to get Nether Fortress mobs to spawn above the bedrock layer by placing Netherbrick above a Nether Fortress (and the bedrock) if there are no other Nether fortresses within 16 chunks of the most extreme points in all 4 directions of the fortress. Check Defanive's Video on youtube for better detils.

Gallery
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