Serpent queen
Serpent queen is a queen of a scaled people, native life of the places where Lumen runs strong. A mage casts Summon serpent queen, and she comes to serve. Her upkeep is paid in geld and mana both, and when it stops she is dismissed.
She strikes with her coils and with lightning, and she aims true. Her scales turn blades. Spells of Bloom and Pyre find her hard to touch.
On the ring of affinities, growth orders itself, so Bloom feeds Lumen. Ordinary folk place her people exactly there: in the fens where Bloom turns into Lumen, where reeds grow wild and then, somehow, in rows. They say her queens rule by counting what the marsh grows, and that nothing in their waters is ever out of place.
It is a lowland story, and it may only be a story. But folk who have seen her host march say it keeps better ranks than their own.