The First-level of Spell Casters was a threshold. One would become an official Spell Caster after getting past that threshold. Otherwise, one would simply remain an Entrance-level Spell Caster. This was the first threshold a Spell Caster must pass.
Following that, Spell Casters had a second threshold, which was becoming a Fourth-level Spell Caster. There was a fundamental transformation between the Third and Fourth-level. Regardless of whether in terms of spell power or cultivating Demon Ability, Fourth-level Spell Casters were a formidable presence.
Therefore, in the Dark Magic Region, one could only build their own individual tower and take in students after becoming a Fourth-level Spell Caster. When Merlin had left the Dark Magic Region, he was merely a Third-level Spell Caster.
