- "Today you will be examined for the Mark of Mastery. Not one but two of the Keyblade's chosen stand here as candidates... but this is neither a competition or a battle for supremacy—not a test of wills, but a test of heart. Both of you may prevail, or neither."
- —Master Eraqus to Terra and Aqua
The Mark of Mastery exam (マスター承認試験 Masutā Shōnin Shiken?, lit. "Master Qualification Exam") is a test for those strong of heart that have been chosen by the Keyblade to become Keyblade Masters. In Kingdom Hearts Birth by Sleep, the exam is taken by Terra and Aqua while Ventus is not allowed to participate because their friend is too young. In Kingdom Hearts 3D: Dream Drop Distance, Sora and Riku partake in the exam.
Kingdom Hearts Birth by Sleep
After an intense evening of training, Terra and Aqua arrive before Master Eraqus, with their friend Ventus eagerly watching. Master Eraqus announces that his old colleague Master Xehanort has come to help judge their skills, then warns Terra and Aqua of the strong heart and will required to pass the test, and that their fate will be decided through the exam. As soon as his apprentices are ready, Master Eraqus proceeds to summon several Balls of Light for them to battle, but although Master Xehanort covertly infuses the orbs with darkness, forcing Ventus to help defeat them as well, Eraqus allows the test to proceed.
Once the orbs have been destroyed, the second stage of the Mark of Mastery exam begins. Terra and Aqua engage themselves in a fierce battle, and as Terra begins to lose the battle, his inner darkness begins to emerge, but he quickly dismisses it.
When the battle has ended, Master Eraqus acknowledges Terra's great strength, but chooses only Aqua to become a Keyblade Master due to Terra's reliance on his darkness. Master Eraqus states that he expects Terra to try harder the next time; he then tells Aqua he will later inform her of her new duties as a Keyblade Master, leaving behind a confused Terra, who soon leaves to get his head together.
Also, Mickey Mouse takes his own Mark of Mastery exam under his master Yen Sid by journeying through different worlds via his Star Shard and aiding Ventus and Aqua in their battles against Vanitas' Unversed. After somewhat foiling the plans of Xehanort, Mickey returns his Keyblade and Star Shard to Yen Sid, believing he has failed, but Yen Sid hands Mickey's Keyblade back to his protege to tell him that he has in fact passed and become a Keyblade Master.
Shortly after sending the letter to Sora, Yen Sid reveals to Mickey that the destruction of both Ansem and Xemnas has caused the reconstruction of Xehanort as well as the return of Master Xehanort so Yen Sid orders Mickey to bring Sora and Riku to him to undertake the Mark of Mastery exam.
Sora and Riku's Mark of Mastery exam involves the two of them traveling to the "world submerged in sleep". This is where the worlds that are not immersed in light or darkness, those of which were not seen during the events of Kingdom Hearts, are found; like other destroyed worlds such as Beast's Castle, the Pride Lands and The Land of Dragons, they were restored following the sealing of Kingdom Hearts, but not completely, thus falling into sleep. The boys' goal is to follow the Dream Eaters in order to unlock the Keyhole of Sleep, restoring the worlds to their proper place.
When first told of what they need to do, Sora is confident in his abilities and does not believe that he needs the Mark of Mastery to defeat Xehanort, but Riku doubts himself because of his previous fall to darkness, so the two of them go together. In the end however, Riku ends up passing the exam while Sora fails after being kidnapped by Master Xehanort and his forces, along with touching the darkness because of his recklessness and failure to protect his heart from the darkness within him. The results of this exam cause Sora to exile himself to Traverse Town to train himself to take the Exam again, where he is greeted by multiple Dream Eaters he had befriended on his journey while Riku stays behind with Yen Sid, bringing Kairi along with him because she is also capable of wielding a Keyblade.
Apprentices of Keyblade Masters that pass the test have two choices:
- The Keyblade Master may take on their own apprentices, and reshape their world to one more of their liking as Master Eraqus did.
- The Keyblade Master may go out on their own journey as Master Xehanort chose to do. Should one choose to embark on their own journey, many different paths open up to them.