"Fascinating creatures, phoenixes. They can carry immensely heavy loads. Their tears have healing powers."

—Professor Albus Dumbledore

The most startling of the phoenix's abilities is its ability to
regenerate itself. It periodically bursts into flames when its body
becomes old, and rises from the ashes as a newborn chick. This event is
called Burning Day, and gives these birds a great life span, as well as the ability to take the full force of a Killing Curse and still be reborn.  Phoenixes are immune to the gaze of a basilisk, which would normally kill anyone who has direct eye to eye contact, or petrify through indirect eye contact.

The phoenix can also disappear and reappear at will in bursts of flames and take whoever is holding them along, similar to Apparition (though like house-elf magic,
they cannot be restricted like wizards are), and boasts magical tears
and song. As stated by Dumbledore, they are extremely loyal creatures,
and are capable of arriving to the aid of beings who share a similar
devotion. This was proven over twenty years ago when Albus Dumbledore's phoenix, Fawkes, arrived in the Chamber of Secrets at Hogwarts to assist Harry Potter in killing the
Basilisk and prevent the Dark Lord from rising. Their tears have potent healing
capabilities. For instance, phoenix tears are the only known antidote of basilisk venom. Their tears are also able to bring a person back even from the brink of death, while the phoenix song will increase the courage of the good and strike fear into the hearts of the evil.  Phoenixes are capable of lifting a great weight with their tails, such
as being able to effortlessly fly up a distance with four people holding
on to its tail. They can also leave messages by bursting into flame to reappear elsewhere, leaving behind a single golden tail feather.