Disguise magic was usually frowned upon by the Mage Association because the latter strived for authenticity and neutrality.
But disguise magic was often abused and used to wreak havoc, causing numerous disasters.
Hence, there were many restrictions placed on disguise magic.
Although it was considered forbidden to learn and study them, high circle mages were still required to learn them because they needed to understand and stay prepared to confront those who disguised themselves.
To summarize, disguise magic was a controversial topic and was rarely used in any discussion to avoid the complications.
Due to such factors, Leonard's current option to understand the disguise magic was through Mirelle or the assassin. Had he known about this type of magic earlier, he would have browsed through his palace's library to check if there was any information.
Alas, there was no such thing as regret.
