Phantom Dragons are very dangerous mobs that possess many abilities. They only spawn in Phantania, usually in groups. They have 100 <3 (the same as a regular dragon) and can be potentially life-threatning without the right tools to fight it with. Despite them being dragons, they are not bosses.
Phantom Dragons very rarely land. When they do, they breathe a blackish fire on any non-phantom mobs that normally kills them upon contact. They often fly overhead, shooting darkish fire charges at the Player while making down-pitched Ender Dragon sounds. Sometimes they wail, which makes the Player's screen shake momentarily. Their eyes can be seen in pitch darkness, making them visible anywhere. Projectiles normally fly through Phantom Dragons. They can whip their tail at the Player, which does 8 <3 on physical contact and does 3 <3 to anything in a 4 block radius of the attack. When killed, they usually drop Phantom Dragon Skulls. They are extra dangerous, since they spawn in groups.
Phantom Dragons only spawn in Phantania.