Ghast

Ghasts are very large jellyfish-like mobs that float through the air and shoot fireballs from their mouths. Their bodies are 4.5 blocks tall, 4 blocks wide, and 4 blocks thick cubes with 9 tentacle-like limbs hanging from the bottom. They first appeared in the Halloween Update. Ghasts are able to spawn anywhere in the Nether, as long as there is sufficient space (5*5*5 space is required to spawn) and the game is not in Peaceful mode.

Behavior
Ghasts normally float around with their eyes and mouth closed and periodically make high-pitched, child-like sounds. They open their red eyes and mouth when attacking. They make a chirp-like noise when shooting and scream pitifully when taking damage. The sounds that Ghasts make have a minimum intensity regardless of their distance, so they often sound closer when they are actually far away. As of Beta 1.8.1, the Ghast will let out a death rattle upon being killed - similar to the death cries that Zombies and Spiders use when killed. Fireballs do not home in and can be deflected if the player hits it.

Unlike most other aggressive mobs, the Ghast does not have a pursuit mode - it does not attempt to draw closer to the player when at long range (and likewise is not particularly likely to float away). Compared to other mobs, the Ghast has a very long search range and can target a player up to 100 blocks away. When the player comes within about sixteen blocks, the Ghast will open fire and attempt to gain altitude.

Ghasts will not fire at the player without a line-of-sight - this can be blocked by Glass, Glass Panes, Leaves, Nether Portals, Vines, Iron Bars, both types of Fences, and Cobwebs - making safe scenic paths through the Nether a viable possibility. When not moving, Ghasts within firing range will face the player, giving the impression that they can see through transparent materials. Ghasts can draw a line-of-sight through curtains of lava, and their fireballs can pass through it meaning players near a pillar of lava can be struck without seeing the source. However, the Ghast can "cancel" its fireball while shooting if the player moves behind an obstruction or builds one.

Ghasts may drop a Ghast Tear when killed, but this can be hard to collect - because it is a flying mob, the tear may fall into lava or an inaccessible area. Ghast tears are a positive potion ingredient, for many useful potions, so Ghast tears are well worth obtaining.

If shot at by a Ghast just try to hit the fireball back at the ghast; if you happen to hit the ghast, it will die in one hit. Doing this will also earn you the Return To Sender achievement. Also, when in the nether, always build a cobblestone wall around your portal to prevent it being destroyed by a Ghast, for Ghasts cannot destroy cobblestone.

Ghast Fireball
The Ghast's fireball attack has a straight trajectory unaffected by gravity and an unlimited or very long range limited in practice only by the confines of the Nether's caverns. Their explosions can often be heard without the impact being seen. At close range, it is one of the most powerful mob attacks in Minecraft, second only to the explosion of a Creeper and the melee attack of an Iron Golem. A direct hit from point blank range will deal 8.5 hearts of damage but damage decreases with distance and is less if the player is simply caught in the blast radius. However, fire damage from a direct hit will most likely kill the player, even if a potion of fire resistance is administered.

Additionally, the projectile is fairly slow and aims slightly above the player's head. When two Ghast fireballs collide, one is deflected to a random direction while the other explodes upon impact. Hitting a Ghast fireball with an item held in hand, an empty hand or a fired arrow will deflect the fireball in the direction of the player's aim. Charged arrows may destroy the fireball instead of deflecting it.

If a Ghast's fireball hits a portal or hits close to it the portal will be closed, requiring re-ignition. If the player manages to get a Ghast to fire at the portal while it is closed, it can be reignited using the fireball. Blocks are also set on fire by the explosion, adding an extra hazard to fighting Ghasts.

The minimum block resistance required to absorb all blast force of the Ghast's fireballs is 20.17, meaning that fences and other blocks with low blast resistance will be destroyed in a fireball explosion.

Cobblestone is a good building material to use, as it is strong enough to resist a Ghast's fireball. Other safe materials include Bricks, Stone Brick, Nether Brick (including Nether Brick Fences), Iron Bars, and Iron Doors. Netherrack should not be used, as it is easily destroyed by explosions, and fires set on it by Ghast fireballs will not burn out.

Fighting Ghasts
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Resistance to Fire
Ghasts may also be set on fire, but Fire and Lava don't actually damage them. A similar effect is seen with Zombie Pigmen. When a Ghast is caught in lava, its movement is impeded, and can then be easily targeted with arrows. At around 23:09 in this video, a Ghast impeded by a lavafall can be seen, and again, but closer and for a longer period of time, at 23:59.

History

 * Ghasts were introduced in Alpha 1.2.0
 * Ghasts and Zombie Pigmen were the first mobs introduced to the Nether.
 * Ghasts used to be vulnerable to fire and lava, but since the Alpha 1.2.2 update, this bug has been fixed and they no longer get hurt when they come in contact with lava or fire.
 * Prior to Beta 1.7 Ghasts aimed at the camera, not the player. Pressing F5 allowed one to easily send the fireball over their head instead of at the character.
 * In Beta 1.6 to 1.8, Ghasts' fireballs did not cause fires, due to a bug.
 * Ghasts used to not be affected by light, and appeared with the same brightness anywhere. This was changed in Beta 1.9 Pre-release.
 * Since 1.9, Ghasts are able to be killed by their own fireballs, allowing the achievement "Return to Sender."
 * Prior to 1.9 you could only injure Ghasts by hitting their tentacles, as their hit box was not large enough to incorporate the body.
 * Prior to 1.0.0, Ghasts used to shoot fireballs with a snowball texture. In 1.0.0, a texture unique to fireballs was added.

Trivia

 * Contrary to popular belief, Ghasts will spawn on blocks. Therefore they can't spawn on transparent blocks no matter how high the roof is. If any transparent blocks protrude into their spawning area (5x5) they cannot spawn.
 * As of 1.1 in .minecraft/resource/newsound/mob/ghast, Ghasts have an affectionate scream, which is a high pitched horn sound (like the classic cartoon tugboat sounds).
 * In Creative Mode, you can go inside of a Ghast by falling through the top of it or flying up underneath it.
 * They can ride minecarts, like all other mobs
 * Originally, Ghasts were intended to be able to spawn near Nether Portals in the Overworld. However, this ability has not yet been implemented.
 * Despite being fireproof, Ghasts and Zombie Pigmen are capable of drowning if under water or lava for too long.
 * Ghasts can cause other mobs to attack it, but the Ghast will never target other mobs; it will only target the Player.
 * It is possible to kill Zombie Pigmen by deflecting Ghasts' fireballs at them. It is also possible to deal a Critical hit on a fireball, since it is an entity.
 * Prior to the full release of Minecraft, when a Ghast shot a fireball, it looked like a flaming snowball; it has since been updated with a new Fire Charge texture.
 * Ghasts are the largest mob by volume - they are eight times as big as the largest variation of slime, but Ender Dragons are longer.
 * It is impossible to 'ride' a Ghast as the player will fall right through it.
 * If a Ghast is trapped in a cube, it will shoot fireballs through the cube. This is because like all other things that shoot, it spawns the projectile one block in front of it.
 * Due to the explosive property of Ghast fireballs, they can be used to mine blocks in the Nether.
 * Ghasts (like all other flying mobs, including the Player in creative mode) can actually fly much higher than y-coordinate 256.
 * Some rooms in Nether Fortresses are big enough for a Ghast to spawn in. However, this Ghast will likely be trapped, as there may not be an exit large enough for it to fit through.
 * A Ghast's eyes appear to be full of tears, though it is unknown why they are constantly crying/sobbing. Strangely, a Ghast only drops 1 tear at death.
 * If a Ghast is killed, any Fireball the Ghast has launched will disappear.
 * Their fireballs can destroy Block 97, but this would kill the silverfish inside of the stone block instead of spawning it.
 * In 1.1, Spawn Eggs are the only way to see Ghasts in the Overworld without the use of mods.
 * If you tweak a Mob Spawner to spawn Ghasts, the model inside the spawner is larger than the frame.
 * Ghasts appear to be 4x4x8 blocks high, but since their hitbox only covers the lower half of their body, they are technically 4x4x4 blocks
 * A well timed arrow can knock back the fireball into the ghast.
 * When aiming with an Enchanted Bow (with at least Power I) at full aim, it will kill a Ghast in 1 hit.
 * Ghast sounds were made by C418's cat.
 * Ghasts don't shoot fireballs at you in Creative mode.
 * A Ghast usually misses hitting the Player when he is standing still as the Fireball travels too high over the Player's head.
 * Despite being very large, a Skeleton has more health points than a Ghast.

Bugs

 * In Creative mode, Ghasts do not become hostile when attacked by the player.
 * Sometimes, if there is a 1-4 space between a platform, they will be trapped, but will still be able to fire at you.
 * Their hitbox data seems out of place. Objects will pass through the top of a Ghast, however, hitting its tentacles will hurt it.
 * Arrows will sometimes pass through the Ghast during server lag in SMP.
 * If spawned in the Overworld using a spawn egg in a glass cage, they will float and stare at the player, but Ghasts will sometimes unexpectedly shoot a fireball in the direction of the player even though there is a glass barrier between them and a player. This bug appears to be absent in the Nether.
 * A fireball will not disappear if in flight when switching to peaceful. However, they do disappear if the Ghast is killed when the fireball is in flight.
 * Ghasts' explosions are less "connected" to them in SMP than in SSP. For this reason in SMP mobs damaged by a Ghast's fireballs will not attempt to attack the Ghast and Ghasts that are either spawned or follow a player into the surface world (see below) can become divorced from their explosions and become an essentially peaceful mob. Similarly, Ghast explosions can sometimes follow a player into the real world, without any nearby Ghasts, but these normally only appear in the form of apparently random explosion noises not connected to actual damage causing explosions.
 * It is possible to deflect a ghasts fireball with a fishing hook, which will cause your line to move with the deflected fireball.
 * Sometimes, attacking a Ghast may not make it attack you when you are at a range of 16 blocks or less.
 * If you get too close and touch the ghast, it is so big that you will see yourself inside the ghast, and the body wall and the stubs of tentacles sticking out of the bottom.
 * In SSP and SMP, after being bumped by a passive mob in the Nether (especially whilst standing in a waterless chicken farm), Ghasts have the ability to target the player through walls and shoot fireball after fireball, creating a tunnel to the player, killing said player. Ghast continues to fire until the player respawns, which can result in anything flammable burning, chests exploding and more. Recreated twice, 20 blocks underground. Also recreated in survival single player in secure house where no entrances where in the line or sight or the ghast in question.