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. Ghasts 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.

Ghasts have an extreme attack range, explosive attack power, and mobility. 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 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.

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.

Ghast Fireballs


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 Skull. 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.

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. Safe materials that are strong enough to resist a Ghast's fireball include cobblestone, 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.

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. Using an external editor, it is also possible to change the explosion strength of ghasts.

Fighting Ghasts
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.) 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. 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.

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.

Video
Note: At 0:39 in the video, it is stated 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, if you can only reach it. Usually, this would be when the Ghast has spawned under a fairly low ceiling, so it can't fly away.

Trivia

 * In Creative Mode, you can go inside of a Ghast by falling through the top of it or flying up underneath it.
 * Ghasts can ride minecarts, like all other mobs.
 * Despite being fireproof, Ghasts and Zombie Pigmen are capable of drowning if under 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.
 * Ghasts are the largest mob by volume - they are eight times as big as the largest variation of slime, but Ender Dragons are longer.
 * 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.
 * 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.
 * If a Ghast is killed, any fireball the Ghast has launched will disappear.
 * 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.
 * If you stand on top of a Ghast's head in creative mode you will see inside of it.
 * On rare occasions, a Ghast will spawn in such a way as to see through blocks (usually trapped on all sides in a tight area). When this happens and the Ghast has 'line of sight' through those blocks, it will launch a fireball in the player's direction. This can be extremely confusing, causing the player to brace for impact, even if no Ghast can be seen.  If left alone and found later, large amounts of the terrain around the Ghast will be destroyed or on fire.
 * Ghasts don't attack if you're in Creative mode, even if you attack it, as they don't have a search mode.