Phoenix is a magical bird that appears in Harry Potter and the Chamber of Secrets, Chapter 12, Moment 1 for the first time.
From the Story
|“||A phoenix is a bird with magical properties. Large and coloured red and gold, they can carry very heavy loads and their tears have healing powers. On their Burning Days phoenixes burst into flames and are reborn from the ashes.||”|
Discovered in Book 2, Chapter 12, The Polyjuice Potion
"Harry sees a Phoenix for the first time on its Burning Day."