A Wizard’s Secret - Chapter 207
The flame sprite mentioned a Spell Caster who had left the ancient monument – it would be Wizard Riesen. His plan had failed when his attack against Merlin did not work, so, he decided to leave Merlin trapped in the ancient monument to die.
Wizard Riesen did not expect that someone or something had observed him this entire time, and although he met the requirements, he had left the ancient monument.
Without the treasures left by the master of the ancient monument, the cultivation methods he claimed for Fiery Collapse would be useless. He would never be able to cultivate the first form of Fiery Collapse.
Merlin saw this as a blessing in disguise. Wizard Riesen had trapped him in the ancient monument and left without the treasure, but he was able to retrieve it. This was extremely useful for cultivating Fiery Collapse!