End Crystal

The Ender Crystal is an entity found in The End. They are found atop the many Obsidian Pillars found across The End, and their primary purpose is to recharge the health of the Ender Dragon, who will charge from the nearest Crystal within a small radius.

When hit by the player they will explode, leaving only bedrock and the tower. The base appears to be made of Bedrock, with a crystal hovering over it and fire engulfing it. The player must destroy a majority of these in the immediate area in order to defeat the Ender Dragon effectively. If the Ender Dragon is recharging its health from an Ender Crystal and you destroy the Ender Crystal it will take a small amount of damage.

Strategy
The recommended method of destroying one of these crystals is to shoot it with an arrow, although snowballs, eggs, and even fishing rods also work, as they are destroyed when hit by any projectile, even ones that do no damage. The player may also climb the pillar and attempt to destroy one by hand or with a sword, but the resulting explosion will hurt the player, and throw them off the tower. The Ender Crystal's explosion is 50% more powerful than TNT, so this can easily be fatal.

Note that while climbing the pillar, the player will be in danger of Enderman attack, and even worse than that, the Ender Dragon knocking them off the pillar.

In order to climb a pillar, players are advised to mine the End Stone around the tower, or possibly Obsidian to build the stairs, since the ender dragon or the Enderman cannot remove either of those materials, instead of creating ladder or stairs out of material that might be vaporized by the Ender Dragon's touch.

Another way to reach the top of the towers is to throw an Ender Pearl up to the top and get teleported to the top, as these are plentiful in the End.

Technical information
The Ender Crystal entity only consists of the wide bedrock-textured slab on and the rotating cubes. The rotating cubes often are mistaken for beacons or glass. The bedrock in the middle is an actual bedrock block which the world generator places in the same location as the entity, and the fire is an actual fire block which is continuously maintained by the Ender Crystal (as bedrock does not ordinarily remain on fire). If there is no solid block below or flammable block adjacent to the fire location, then the fire will not show up, but the crystal's attempts to do so will create flashes of light in the area, and any flammable blocks nearby will catch fire. These lighting updates may be responsible for lag noticeable when an Ender Crystal is created outside of its normal position.

The Ender Crystal entity is not solid and can be walked through freely. An Ender Dragon will pass through the crystal with impunity.

Ender Crystals can be pushed by pistons, but doing so in order to align them with a block causes them to explode. If they do not explode, they will be set on fire, to no effect.

Bugs

 * If an Ender Dragon passes through one, the explosion sprite will appear, as the Dragon destroys the fire block.
 * When created naturally, they are layered directly over a Bedrock block, which is most noticeable when viewing one from below. The player may see glitching of the textures where the two overlap.
 * Crystals can be placed on blocks at max world height but they will not cast light.
 * It is very rare, but possible, for an Ender Crystal to spawn one block above the obsidian pillar.
 * In 1.3.1, when you destroy it, the fire will stay. In creative, if you destroy the bedrock, the light of the fire will stay.
 * When an ender crystal is struck by lightning, the game crashes.
 * A ender crystal spawn egg will not spawn an ender crystal. (Only tested in 1.4.2)

Trivia

 * Placing water above one using a Bucket will cause a looping effect, where as the fire is continuously put out and reinitialized as the water attempts to flow down and is stopped. The water will not spread, as it can flow downward, but is being prevented by the reoccurring fire instantly taking its place.
 * The healing beam is neither obstructed nor is it diminished by entities or blocks.
 * A chain reaction of Ender Crystal explosions is instantaneous.
 * No wall can stop an Ender Crystal explosion reaching another crystal in range.
 * The Ender Dragon will be hurt when the player destroys an Ender Crystal when the Ender Dragon is healing with said crystal.

Gallery
Enderkristall Cristal d'ender Kryształ Kresu 末影水晶 Кристалл Края