Phantom

"This manta-ray–like monster is a flying creature that spawns at high altitudes. It is attracted to insomnia, and will find players who haven't slept for many days. It will swoop down in groups and bite your flesh."

- Jens Bergensten

Phantoms are flying common undead hostile mobs that attack players who haven't slept in over three in-game days.

Spawning
Phantoms spawn in the Overworld at night; high above players that have not slept for at least 3 days. Phantoms will spawn more often the longer a player has gone without sleep.

For phantoms to successfully spawn, the player in question must be above sea level and not have a block above its head which blocks light in any way (for example leaves won't work as they have a light opacity of 2, but glass will work as its light opacity is 0).

Once the conditions are right, a pack of 1–4 phantoms attempts to spawn 20–34 blocks above the player, and off to the side by up to a taxicab distance of 9 blocks, every 1–2 minutes. The chance of a successful spawn is $x-3⁄x$, where x is the number of nights since the player has slept, which comes to a $1⁄4$ chance on day 4, a $2⁄5$ chance on day 5, a $3⁄6$ on day 6, and so on.

Phantoms are counted towards the hostile mob cap, but don't respect it when spawning. Their spawning mechanic is based on the location of players in the world, not by randomly choosing a block near the players like regular mob spawning.

Drops
Phantoms drop 0–1 phantom membrane when killed, which can be increased with the Looting enchantment.

Behavior


When idle, phantoms will fly around in a circle at a constant y-elevation, leaving a trail of gray smoke while doing so. They have a quite large search radius, and will occasionally either swoop down or up quickly to attack their victim. If stopped or hurt during this action, the phantom will retreat back to its original elevation. When idle over water, the phantom will sometimes swoop into the water and will die as it is not pushed back up.

In water, the player is at a large disadvantage to the phantom, as the phantom's motion is not affected by water.

When under the Invisibility effect, the phantom's body will disappear, but its eyes and smoke particles will still be visible.

Phantoms will burn in sunlight. Like other undead mobs, they are harmed by the Instant Health effect, healed by the Instant Damage effect, and immune to the Poison and Regeneration effects.

Trivia

 * Phantoms have a Size tag, which determines the size of the mob.
 * The phantom was added into the game as as result of winning the Minecon Earth mob Twitter poll as "Mob B".
 * Phantoms are currently the fastest non-boss mob in the game, traveling at speeds of up to 20.83 blocks per second.
 * At one point before the release of 18w10a, the phantom texture was made red, but it was decided that it appeared too much like a nether mob.
 * The phantom was originally going to have a mouth, like the sketch shown during MineCon, but it was eventually scrapped because "it looked so much like a muppet".