Star mage
Star mage is a caster of the astral peoples, the native life that gathers where Lumen runs strong. A mage casts Summon star mage, and one of these casters comes to serve.
It strikes from a distance, first with raw power and then with lightning, and it moves quickly. The card shows how hard. Mana sustains it, so its upkeep is paid in mana, and it goes when the mana is withdrawn.
It has no Core. A Sealborn's spells are held in a core and must be recovered after every recasting; this caster's power is simply its own, part of the life Lumen makes where it runs strong.
Sealborn tell a story about that difference. In the Age of the First Sealborn, when newcomers first learned to cast, the astral casters are said to have watched them and thought them clumsy children, fumbling at what their own people did by nature. The Sealborn tell it as a joke against themselves.