The mirror of Eris is one of the most interesting objects in the magical world. It is powerful, it can show people's deepest desires, it is addictive and therefore dangerous. The mirror of Eris is regarded as the last level to protect the philosopher's stone, which embodies Dumbledore's wisdom.

It was only after Professor Dumbledore made a key modification to this mirror (the mirror was hung in the room of requirement for centuries before it was put into practical use) that it became an ideal place for hiding things and the ultimate test for exploring new soul.

The use of the mirror of Eris

Dumbledore found that Harry's inner desire was that his dead parents could be reunited with his family. This simple and kind wish made Dumbledore very relieved. If Harry is influenced by the fragments of Voldemort's soul and regards himself as the leader of the wizard in prestige, it is simply the next Grindelwald.

Although Dumbledore himself saw Grindelwald in the Mirror of Eris, he never wanted to see Harry become a new generation of Grindelwald in reality. This is also the last stage for Dumbledore to make the Mirror of Eris safely.