Seasonal Magic

Man of Miracles by Lee Rosenblatt

There is a raw, formless source of magic that mortals both arcane and divine can both access. Ok, I'll bite. The Weave helps protect the world from the dangers of unrefined magic. Sure. It's ever-present, flowing freely throughout the Planes and their worlds, touching every corner of existence. Cool. It's static and stale and everyone who casts the same spells regardless of time and day and year and location but end up with the same results and spell effects. Nah, I don't buy it. 

Picture an ocean as it flows endlessly into the horizon, forever blue. Sometimes it has an overwhelming tranquility, and other times it crashes with a pure and unbridled sense of violence. But if it flows, it also ebbs. Just as the tide rises and falls, and the seasons come and go. As a fundamental feature that ties together and connects all the continents, so too does the Weave as it acts as a cornerstone of all Planes of Existence.  

That answers the question as to why Wizards and Sorcerers of yore were vehement students of astrology. They studied the conditions in which the Weave ebbed and flowed through the firmament, making bold predictions and stern warnings to those who wouldn't understand the signs. They measured eldritch precipitation levels, barrier pressure, astral convergence, strato-divergence, and everything in between. Cloud readers, skytalkers, and stargazers are the frontline of interpreting the Weave-weather.

Man does not weave this web of life. He is merely a strand of it. Whatever he does to the web, he does to himself. - Chief Seattle

Each season brings a different type of magic to the forefront, as if there's a little more pressure pushing it through the metaphysical valves between the Weave and the physical world. I like to imagine each school of magic as having different figurative densities. Instead of being layered neatly on top of another, they tumble around in a boiling cold mass of magic energy, escaping through whatever-sized holes that fit their volatile chunk of eldritch jiggliness. Sometimes abjuration magic congeals into perfect platonic polygons, slipping through existence with ease like a game of 5-D Perfection! The heavenly bodies will shift into the next cycle, and now magicules of divination magic form perfectly tesseracted entanglements that were both never there and always there to begin with.

Bring that picture of the ocean that you made in your head a few seconds ago back up. Now add some clouds. Now zoom out and picture drift patterns and their ebb and flow and earthly cycle throughout the year. One more step. Multiply that by eight extra dimensions, in every time-direction and flavor. Now you're starting to get the picture. That's the Weave in all it's fanta-magical goodness. THAT'S the thing we're supposedly dipping our Mage Hands into and chucking Fireballs from with precision and consistency every day of the year? Riiiight. So let's dive into Magic Meteorology, and take a big, deep whiff of that magic-pollen of the Planes.

The Seasons of the Weave

Arimathea (abjuration). Spell effects are more vibrant and shine brighter than normal. What spells were once invisible, can now be seen with a dazzling translucence, with wisps of shining brilliance. Some shields and wards may be twice as strong in some areas or last a touch longer.
Eshoya (conjuration). Summoned creatures are more excitable and have an air of enthusiasm and focus as if in heat. They might also be sporting a more atypical coloration and pattern. Summoned objects might be made of finer materials, or show signs of warping reminiscent of storybook stylization, yet retaining full functionality. 

Nostrad (divination). Spells of this school might have lingering effects, like the caster leaving an after-image or even a before-image. Irritation, itching, or even glowing eyes are also a common symptom. 

Aphrod (enchantment). Effects linger and dance in the air like sprites in the wind, and any casting exudes a peculiar and distinct, 3-dimensional smell unique to the caster. 

Yperion (evocation). It takes much less effort to pull these spells from the Weave, and more effort to control them, like turning on an unfamiliar faucet for the first time with eldritch energy spewing forth in a forceful turrent. Even the dice explode, so watch your fingers on failed casts.

Lok (illusion). There's a small chance that, if the illusion is convincing enough to those that see it, it might actually be made real through egregore that makes it so. Images are more vibrant, sounds are multi-channel and perfectly mixed, and smells trigger lost memories you've never had. 

Oris (necromancy). Necromancy is already a tricky style of magic to use properly, opening the right channels to various flavours of After-|Living. The waters of the Weave are a little less dense, and a little more buoyant, allowing some of the more....motivated or zealous souls to find it easier to hitch a ride back into the world of the living through any small crack or opening created by careless wizards.

Osthane (transumation). Although the Immutable Laws are never broken, during this season they can sometimes be....bent. The market of the Weave is a fickle mistress, and sometimes equivalent exchange expands and contracts in one direction or another, which might have a slight influence on the value of things lost or things gained, leaving one side of the transaction uneven.