Ascended by use of Artemis to get from Superior to Rare. Artemis can be obtained by completing her trial and leveling Kestra, Amani, and Erasmus to 25.
Note that at L31 Kestra obtains a new skill but no longer gains any mana. Although she is going to get future Artemis to ascend all the way to legendary without extra mana it would seem very limiting.
We show the maximum spells at each rarity for you to easily compare.
Max Superior Stats: Level 25-30
Rare Stats: Level 35-40