The Gift of New Grasses

The King and his Knights stayed at the back of the crowd of villagers, who had fallen deathly silent to a man. All eyes were on the elder, who had dressed himself in ritual finery. All feathers and corded fibers. One ancient hand gripped a staff tightly, magic gathering in the gnarled prongs that formed the staffs head.

The mass of raw magic grew brighter and brighter, until it was hard to look at directly. Gowyr turned his eyes to the night sky to give them a respite, and saw other pillars of similarly emerald light rising into the night sky. Other villages, doing the same ritual, he had to assume.

Suddenly, the elder slammed his staff into the ground as if responding to an unseen signal, and all the magic he had gathered traveled down the length of it and into the ground, emerald light shinning through the soil and grass, appearing almost like it was going to burst back into the open air as it spread away from the elder like a stone's ripple in water.

AS the light traveled farther and farther away, it was like the ground itself had bring to life. Looking as if it had begun to writhe and move. The King looked out to the fields around the village, fallow since the previous season, sprung to live. Green shoots climbed towards the sky before his eyes, and as they grew taller than his prodigious height, shifted to a golden amber tone.

— The Threemetal Cycle, by Krattipos of Salassa

On the frontiers of the world, as well as the farming communities, rely on magic to survive and support their population. On Avallus, this takes the form of a yearly (sometimes multi-yearly, depending on the fertility of the soil of a given region) known by many names but if you were to call it the Gift of New Grasses most would know what you were talking about.

It's operation is, comparatively, simple to the spellwork that cabals and court mages make use of, mostly being a brute force gathering of magic and then infusing it back into the soil, but that magical strength is not easily found even on the frontier. It does, as a side effect, cause farming communities to form and be propped up by those with prodigious magical strength, for their way of life and population require them.