After Almond was done fine-tuning his Regalon Spirit Engravings and Prime energies, he began training in his Emperor-ranked Prana Art—Devouring Eternity's Law.
His Prana Sea was 2750, but he had his Soul Sea and Soul Avatar refined till 2898 with the new Soul Art he had brought four months ago from the Academy's store. It cost him 100,000 Academy Points, but he chose it because he felt more proficient in it and progressed faster, which turned out to be true.
Rin and others also bought Soul Arts they found suitable for themselves after earning Academy Points.
Of course, the common theme of practicing Soul Art didn't change—getting tortured. However, Soul Arts could let one choose what kind of torture they preferred to endure in the long term, and naturally, the rank of Soul Art meant faster progress.