The Test of Truth and Heart

The test that any apprentice who wants to take the step towards Magus and Master must take. It shows the truth of the apprentice and shows both their heart and mind bear for all to see. This is the final test of all who wish to become a Crystal Mages. You can choose not to take the test with no consquences other than never being being asked to step up beyond those most advance apprenticeship of the Crystal Mages, but many Apprentices of the Crystal Tower are more powerful than many Archmages within the city or across the planes.
The test itself is a mental and physical exam, to show the Truth of the apprentice mind, and the strength of their soul and body. Many fail, some die. You can only fail this test twice on the third you are forever barred from taking it again. You must prove you stand for the believes and articles of the Crystal Tower, and you won't fall to the darkness or misuse the advance knowledge of the tower.
The test is taken at any point an apprentice feels he is ready, he requests it of their master who arrranges it with the higher circles of the tower, to arrange and to the actually put the apprentice to the test. Most apprentices will take their first attempt as a young adult for humans around 16 to 20, and the other races take a similar mature in their own cycle of life.
The test is multiple stages one to test loyalty to the tower, one to the test knowledge and the final to test strength of soul and heart. Each test is different for each apprentice as it is customised to their potential weaknesses. Few talk about the tests in success or failure, occasionally an apprentice is never seen again after pasting though the portal to the testing rooms, and no Master involved would every talk about it to anyone who wasn't there. Each is private and failured isn't a black mark against an apprentice name, just a guide to what they need to work on before coming back to the room and to try again.