Magic would be vaguely, but not completely, based on the spheres system. Each sphere could be studied, allowing the studier to use spells of that sphere. The more powerful spells would be unlocked later than less powerful spells. A creature, if it lived long enough, can learn all magic spells. The magic spheres would consist of: Nature, Weather, Art, Death, Fire, Water, Earth, and Sky.
NATURE SPELLS
Turning an enemy into an animal
Turning the user into an animal
Turning the user into a humanoid animal
Turning an animal into a humanoid
Taming an animal
Turning an enemy into a plant
Creating plants
Creating trees
Healing themself
WEATHER SPELLS
Controlling the weather
Shooting lightning
Freezing enemies
Flying
Giving allies the power of flight
Changing biomes
ART SPELLS
Summoning artifacts
Improving items
Creating music
Making enemies friendly
Engrave walls instantly
Become perfect at artistic skills
DEATH SPELLS
Kill enemies
Animate corpses
Give enemies syndromes
Banish ghosts
Live without a head/brain/lungs etc
FIRE SPELLS
Shoot fireballs
Shoot fire
Be fireproof
Use forges/smelters/etc without fuel
Destroy flammable things
Breath in magma
Put out fires
WATER SPELLS
Breath underwater
Swim fast
Become a fish
Summon fish in water
Walk on water
Freeze water
Clean things
Summon drinks
Make water drinkable
Block water
EARTH SPELLS
Generate obsidian from magma
Transmute materials
Turn enemies to stone
Prevent cave-ins
Dig without a pickaxe
Move through walls
Climb well
SKY SPELLS
Teleport
Predict the future
Change the time of day
Change the season
Stop time
Seeing without eyes
Seeing through walls
Seeing in the dark
Prevent a werebeast from transforming
Causing a werebeast to transform
Blinding an enemy
Turning invisible