Before Andar could take such a drastic step as going against the Supreme Mage, he needed to be fully prepared, if such a thing could even be prepared for, but over the years, as he grew stronger as a mage, he had been able to gather a lot of spells and unique abilities that pushed his powers to realms unknown.
His talents in all Immortal Arts had grown by leaps and bounds, including Alchemy, Weapon Refinement, Formation, Talisman Crafting, Spiritual Plant, and Puppet Creation. Unlike other mages who only focused on one of these crafts, Andar took all of them.
This would be considered madness, but he had seen someone who was far greater and thought the entire Immortal Arts of the Mages to be nothing but a tiny portion of the absolute truth behind eternity. Andar knew he could not be equal to the breadth of his father's knowledge, so he pursued the depths of the Immortal Arts, wanting to become the first person to completely master and supersede them.