Ghast

Ghasts are very large, jellyfish or ghost-like mobs that float through the air and shoot fireballs from their mouths. Their bodies are 4 blocks tall and 4 blocks wide with 9 tentacle-like limbs hanging from the bottom. They first appeared in the Halloween Update. Ghasts are able to spawn above any non-transparent block in the Nether, as long as there is sufficient space (at least a 4*4*4 space, with the base centered above a solid block) and the game is not in Peaceful mode.

Behavior
Ghasts normally float around the Nether with their eyes and mouth closed and periodically make high-pitched, cat- or infant-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 on the player, and can be deflected if the player hits them with an arrow or melee attack. 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 Regeneration potions, and are very valuable on most servers with economies, so Ghast tears are well worth obtaining.

When in the Nether, always build a cobblestone wall around your portal to prevent it being deactivated by a Ghast, for Ghasts cannot destroy cobblestone.

A Ghast fireball will deactivate an active portal, but a second fireball will (re-)activate the inactive frame. (Or you can just use a flint and steel or a fire charge.)

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, third only to the explosion of a Creeper and the melee attack of an Iron Golem or the explosion of a wither skeleton skull powered by a Wither. 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 unprotected player.

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. Again, a Ghast struck by its own fireball (or even another Ghast's fireball) will be killed instantly, however this is very hard to do.

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, obsidian, 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.

On multiplayer if you log out when a ghast fireball is flying when you log back in it will slow to a stop and can be hit to launch again (at your aim)

Similarly, a ghast fireball may be used as a personal weapon that explodes on contact. This can be achieved by using an external editor such as MCedit to turn a stationary fireball (which can also be created using external editors) into a spawner which spawns the aforementioned entity to a set position. The player can then cover the stationary fireball with water (to prevent damage in case of a misfire). Once the player has done this they can punch the fireball in any direction which serves as a very effective turret.

As of the 1.4 update it is possible to change the explosion strength of ghasts with external editors.

Fighting Ghasts
Ghasts are often considered the most difficult mob to kill in the Nether owing to their extreme attack range, explosive attack power, and mobility. They are also quite common; players in any exposed area will have to deal with them sooner or later and possibly from the moment they step out of a portal. Ghast fireballs have a profound effect on Nether architecture, making a compelling case to use only materials resistant to their explosions for outer walls and exterior fittings in places where their fire may be drawn. Not only do the explosions have lots of knockback, but they can break blocks under the player... and the Nether has many thin floors. Thus, players are vulnerable when caught in unknown and/or precarious territory, and especially when building (when they may not be able to move freely, and might be perched above a long fall).

Fortunately, their aim is poor at most ranges, especially if you're moving. Also, Ghasts don't actually pursue the player. This means you can hide behind cover, and they won't just chase and corner you. On the flip side, they hardly need to chase you and you can't easily lure them into range (or traps).

Most Ghast kills are made with a bow and arrows because of the Ghast's position in the air. Unfortunately, they are agile, and it will usually take at least two or three arrows to kill them. (More specifically, a plain bow will take one or two hits, though a suitably enchanted bow can kill them with one fully charged hit.) When aiming a bow, players should lead their shots as Ghasts can quickly change trajectory and move quite quickly. Depending on the Ghast's range and relative altitude, it is usually necessary to also aim at a high trajectory to gain extra range. Where possible, having the advantage in altitude (such as shooting from the topmost layer of the Nether) is of enormous help.

It is also possible to kill Ghasts by deflecting their attacks back at them. A deflected fireball will kill any Ghast in one hit, and even a near-miss may damage them with the explosion. The biggest advantage of doing this is that Ghast fireballs are infinite, while a player's arrows are not. (You also get the Return to Sender achievement.) However, "fireball tennis" is a bit trickier than it sounds. Besides the Ghast's agility, properly deflecting the fireball needs good timing and/or luck, and usually risks taking a direct hit. The player can deflect a fireball by hitting it with anything before they impact, even bare hands. Because of their low speed, spamming mouseclicks is often enough to deflect a fireball. Shooting at the fireball can also deflect it; this works with not only arrows, but snowballs and even fishing rods. The fishing rod, when released, slightly affects the fireball's trajectory. This relationship goes both ways and a Ghast's constant stream of fireballs may well interfere with a bow's firing arc.

A Ghast can be killed with melee weapons if the player can get close enough -- indeed, 2 blows from a stone sword will destroy one. Ghasts are especially vulnerable when caught under low ceilings, or even when they happen to come within sword's-reach of the ground. It is possible to use a fishing rod to draw Ghasts into sword range... if they're already in range of the rod. A close Ghast is also much easier to hit with a bow, though reaction time against its fireballs is likewise lessened.

To instead dodge fireballs, move from side to side, rather than running away. Ghasts fire slightly above and/or behind the current location of the player, from the Ghast's point of view. This means that a player running away is 'more likely to get hit -- the fireball will be aimed just about where they're running to.

Much like using neutral or enemy mobs as shields against arrows fired by Skeletons in the regular world, it is feasible to use Zombie Pigmen as shields against Ghasts in the Nether. It is possible to injure or kill Zombie Pigmen in this fashion without ever making them hostile to the player.

An effective method of fighting Ghasts is to make a shelter, preferably out of brick, cobblestone, obsidian, or other explosion-resistant materials. Make a 1x1 hole in the roof and add ladders leading up to it, in such a way that you can poke the upper half of your body through the roof. When a Ghast is near, climb the ladder, shoot an arrow at the Ghast and quickly descend again into your explosion-proof shelter. This should mean that you can kill Ghasts easily with minimal health loss. However, the ladders may get blown up/burned down by the explosion. To improve this even further, add a small 3&times;3 roof 1 block above the hole in the main roof. Most of the Ghasts' fireballs will now hit this roof rather than you, meaning that you should be safe against most Ghast attacks. If you have the cobblestone, making the shelter larger than 3&times;3 will allow for both exits, and cover from all directions. Iron bars make good windows for these shelters, but won't hold ladders.

In addition, a more range reducing method is to grab a Ghast coming relatively close to you and attempt to hook it with a fishing rod, after hooking it with a fishing rod, right click again to bring the ghast closer to you, this will allow you to take a better shot with your bow, or better yet, a blow with a sword in hand. To be better with this method, optimize your inventory for this so that you can take advantage of the reduced range.

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 and all other Nether mobs. 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.

Video
'Note: At 0:39 in the video, he says that the player can only kill a Ghast with an arrow, or with deflecting a fireball. However, this is not true. It is possible to kill a Ghast with a sword, although hard unless you are in a cavern with a ceiling that is high enough for a Ghast to spawn, but low enough that you can hit it.

Bugs

 * Sometimes, if there is a 1-4 space between a platform, they will be trapped, but will still be able to fire at you.
 * 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.
 * In the Xbox 360 edition, fireballs usually just stays there and shaking violently, after being shot by ghasts, which makes it difficult to build or destroy.
 * 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 the player. The 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 were in the line of sight of the Ghast in question.
 * Ghasts will not become hostile to the player in creative mode no matter how many times you hit it.
 * If the player positions the camera below the body of a Ghast, viewing only the tentacles, the Ghast is no longer visible.
 * If a Ghast comes in contact with cobweb, their AI will bug out, causing them to rapidly spin around.
 * If the "/gamerule mobGriefing" command is set to "false", ghast's projectiles will still destroy blocks.
 * If the game is set to peaceful when a Ghast launches it's fireball, the fireball will be frozen in place for a while, before it eventually despawns. It still does not move if the game is set off of peaceful.

Trivia

 * In Creative mode, if you spawn a Ghast in an area smaller than itself, it will suffocate and die.
 * Contrary to popular belief, Ghasts must spawn on at least 4x4 solid block.
 * 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.
 * Despite being fireproof, Ghasts and Zombie Pigmen are capable of drowning if under water 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.
 * Ghasts are the largest mob by volume - they are eight times as big as the largest variation of slime, but Ender Dragons are longer and Giants are taller.
 * 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.
 * On a Ghast, the tears are black. However when a Ghast Tear is dropped, it's white.
 * 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.
 * As of 1.4m, the only 2 ways that Ghasts can be in the Overworld are Spawn Eggs and a Ghast going through a Nether Portal.
 * If you tweak a mob spawner to spawn Ghasts, the model inside the spawner is larger than the frame.
 * When aiming with an enchanted bow (with at least power I) at full aim, it will kill a Ghast in 1 hit.
 * C418 revealed in an AMA on Reddit that the Ghast sounds are taken from his pet cat, which he makes when disturbed while sleeping.
 * Despite being very large, Ghasts have less health points than most hostile mobs.
 * If the player leaves the Nether while a fireball is still flying through the sky, it will be motionless in the sky if the player returns. When hit with an arrow, it will react like normal and fly in the opposite direction from where it was hit.
 * In SSP, if a Ghast fires a fireball, and the player saves and quits to title, then switches into Peaceful mode, then reopens the world, the Ghast will disappear, but the fireball will slowly stop. The player can punch the fireball or hit it with an arrow or snowball, and it will react like normal and fly in the opposite direction from where it was hit. The player can not place blocks near the frozen fireball, because it is an entity with a hitbox, unlike items.
 * When deflected by a sword with the Looting Enchantment, a Ghast fireball will inherit the enchantment in question. If that fireball were to then kill the Ghast, the effects of looting would apply to its drops.
 * Despite being similar to ghosts, the Ghast is not an undead mob. (Tested and confirmed)
 * Ghasts are slightly bigger than the Wither,but the Wither is more agile and aggresive.