To evolve from Legend Rank to Mythical Rank, a Spiritual Beast needed to accomplish three things.
First was crafting a piece of Corona Equipment.
Just like before, crafting the Corona Equipment required at least two, and at most nine, Corona Equipment Materials and one Equipment Forging Stone. The more materials used, the higher the grade of the perks after crafting; however, the success rate correspondingly decreased.
Although it wasn't explicitly stated in the rules, it was anticipated that under similar conditions, the success rate for crafting Corona Equipment would be much lower than that for Moon Halo Equipment.
Just like how Moon Halo Equipment had a lower success rate than Starshine Equipment.
Successfully crafting a piece of Corona Equipment was merely the first step in the evolution.
After that, it was necessary to enhance the previous Moon Halo Equipment.
