Every lesson Randy has learned makes him a Ninja. The ninjas has been kicking Sorcerer’s butt for hundreds of years, and he’ll still be doing that now.
Interestingly enough the Nomicon makes the bare minimum effort to clarify Randy's mistakes, which is a very bad thing for a mentor to do. But I guess the Nomicon's method of teaching is letting Randy commit the mistakes so that he can learn from it first hand. On one hand it's irresponsible, since there's numerous times when making a mistake can have serious consequences, like in the epsiode when all the students thought Bash was the Ninja, Randy was about to reveal his secret, and the Nomicon did nothing to stop him. But on the other hand it can be seen as the Nomicon respecting Randy's judgments and giving him the space to learn on his own, like in the epsiode with nomirandy, where needed to learn balance. Very interesting, I have to say.
On Saturday September 2, Miraculous Ladybug season five finale episode recreation the final day part two the final battle of Marinette Vs Gabriel like Randy Vs the sorcerer