Ender Dragon

Ender Dragon
The mighty Ender Dragon is one of a kind—a vast, flying creature with void-black scales and purple eyes. It soars above the central island of the End. No one can say whether it is a guardian or a prisoner of the End, but either way, the Ender Dragon challenges anyone who enters its domain.
The Ender Dragon buffets enemies with great wings, engulfs foes with its gaseous breath weapon, and delivers crushing bites with its powerful jaws. Its hide is strong enough to deflect all but the deadliest weapons.
End Crystals
The Ender Dragon has a special relationship with the ten 40-foot-tall obsidian towers scattered around the central island of the End. At the top of each tower is an End crystal that sends a beam of healing energy to the Ender Dragon when it flies nearby. If slain, the Ender Dragon can be brought back to life by placing four End crystals on the portal that leads back to the Overworld.
Crystal Healing
When the Ender Dragon ends its turn within 60 feet of an End crystal, the crystal emits a healing beam that causes the dragon to regain 20 hit points. The dragon can benefit from such healing only once per turn.
Crystal Statistics
An End crystal is a Large object that has Armor Class 11; 30 hit points; vulnerability to bludgeoning and thunder damage; resistance to piercing and slashing damage; and immunity to poison and psychic damage. When a crystal is destroyed, it explodes in a 20-foot-radius sphere of destructive energy. Any creature in that area must make a 15 Dexterity saving throw, taking 21 (6d6) force damage on a failed save, or half as much damage on a successful one.