Clarent

After creating a few more skillbooks from his techniques, Draco send them over to the Guild Shop since Vita City-State was a property of Umbra, he could deposit them directly from here. 

After that, he prepared a Master Rank cup of coffee that removed the <sleep deprived> status for 24 hours. He then meditated on his subjective magic and the techniques from the Serpent God Inheritance for the rest of the night. 

He had to train up his Cause and Effect Theory in order the strengthen his willpower and concentration. While both could be greatly augmented with external means, he wanted to buff up his base quality. 

As such, daily practice was imperative. Even though the gains greatly diminished over time, this was the best stage. 

One thing many people didn't want to acknowledge when doing something repeatedly in order to improve was that there would always be diminishing returns.