You can see them in the "Characters" section in the main page of the novel, however, you can't really see them well there, so, I'll pinpoint all the characters whose art I made here, and I'll comment on them with the picture, so you can take a better look, and comment if you want to.
Just click in the comment of each one and you will find them.
※※※
» Chaos
[spirit guardian of chaos magic] [male]
» Laverna
[spirit guardian of thievery magic] [female]
» Frost
[spirit guardian of ice magic] [female]
» Chrony
[spirit guardian of time magic] [male]
» Alma
[spirit guardian of soul magic] [male]
» Raiden
[spirit guardian of thunder magic] [female]
» Castin
[spirit guardian of empathy magic] [male]
» Greeny
[spirit guardian of sound magic] [male]
» Mina
[spirit guardian of mind magic] [female]
» Davina
[spirit guardian of divination magic] [female]
» Atlantia
[spirit guardian of water magic] [female]
» Lumos
[spirit guardian of light magic] [male]
» Darkling
[spirit guardian of shadow magic] [male]
» Vulcan
[spirit guardian of fire magic] [male]
» Winstor
[spirit guardian of air magic] [male]
» Terra
[spirit guardian of earth magic] [female]
» Gravitor
[spirit guardian of gravity magic] [male]
» Samantha
[spirit guardian of spatial magic] [female]