The concept of 'Lex Metamorphis' is that all Jurists should be provided with direction on what the 124 Subjects & 7 Categories of the Global Tablet of Jurisprudence are - namely, the 124 Subjects & 7 Categories actually defined by independent & widely used Legal Dictionaries (e.g. Stroud's & Osborne's).
Legal dictionaries are of course massive & it is impossible for the human mind to know it all, but knowing these 131 definitions is cornerstone legal knowledge.
This is the simple but extremely important starting base for anyone who wants to become a powerful jurist. Once a jurist knows this, they know how to research any question of law they may face.