Ooo, I know magic, I can translate the circle!

The circles filling up are either just that, representing a container filling up, or represent the moon.

While I can't identify the runes, I saw Dagaz. That was the only rune I recognized so it could be a coincidence.

The arrows in the center make a compass rose. That could represent expanding, or simply all directions.

So I'm guessing the circle is for having someone grow, possibly by filling their stomach so they expand in all directions?

Very compelling!