That's why I think Primal and Nature should be different list. I'd have 7-10 different power sources. But we're past that.
I think an exercise to create about 20 spell spheres can be an exciting one!
Fire - Burning Hands, Scorcher, Ray of fire, Fireball, Wall of fire, Firestorm, Immolation, Flaming Strike.
Earth - Stone Skin, Bones of the Earth, Stone Shape, Meld into Stone, Shape Earth, Earthquake, Stone Wall, Sand Wall.
Storm- Storm sphere, Sleet Storm, Conjure Lighning, Control Weather, Lightning Bolt, Chain Lightning, Ice Storm.
Void and Star: Levitate, reverse gravity, Etheralness, Minute Meteor,
Wind - Wardind Wind, Feather Fall, Gust of Wind, Wall of Wind, Fly,
Water - Tidal Wave, Tsumani, Control Water, Wall of Water, Cone of Cold
Plant - Entangle, spike growth, wall of thorns, Giant Vine,
Beast - Shapechange, Alter self, beast sense, Giant insect, Insect plague
Charm -Charm X, Dominate X, Irresistible Dance, Enthrall, Compulsion, Suggestion
Enchant Item - Magic Weapon, Elemental Weapon, Instant Summon, Fabricate
Conjure Chaos - Summon X demons, Sumon X elemental
Conjure Law - Conjure Celestial, Planar Ally, Gate, Hold X
Conjure Spirit - Conjure Fey, Conjure Woodland being, Conjure animal
Create & Destroy Life - Heal/Harm, Cure/Inflict Wounds, Blight, Contagion, X Restoration
Exorcise Good & Evil -Banish, Banish good and evil, protection from good/evil, Hallow, circle of power
Warding -Protection from Energy, Elemental Bane, Protection from Poison, sanctuary, guard and wards, symbol of warding, resilient sphere, Magic Circle
Second Sight - See Invisibility, Tue Sight, Speak with Dead, Darkvision
Tongue of Fire - Comprehend Language, Command, Tongues, Telepatic bond, Shatter
Shadow - Shadow Blade, Darkness, Creation, Black tentacles, Shadow of Moil
Phantasm - Invisibility, Greater Invisibility, Mislead, Mirror Image, Phantasmal Killer, Crowm of Madness, Weird
Fate - Bless, Bane, Hex, Enhance Ability, Enhance Skill, Deathward
Knowledge - Identify, Read Thoughts, Legend Lore, Locate Object, Locate Person.