tangentially, does anyone think it's odd that for a system that references the four elements structure so often that there is no proper 'earth' energy type, (lightning being associated with air happens enough that i can buy that being the 'air element'), similarly i feel like we're really missing a 'nature' energy type for plant based magics and such.
I look at the Weapon damage types, namely Bludgeoning, Slashing, and Piercing as the "
Earth" damage types. A weapon like a Sword is made out of metal and is clearly the "Earth" element. But Acid is the Earth "energy", the kind of Earth that is found within the Flux of the Primordial, Elemental Chaos.
Air with Thunder and Lightning works well enough.
Water with ice, whence Cold, works well enough. Where Fire and Water are "opposites", so are Fire and Cold damage types.
Fire as a state of matter is plasma, relating to the sun and stars, whence the Radiant damage type. Meanwhile Fire is more strictly "heat" damage.
Plant as the element, "Tree" or "Wood", I think of as a special mix of the other four elements, Fire (sunlight for photosynthesis, and burning wood), Air (oxygen, and growing up high into the air expanding and encompassing like a gas), Water (for nourishment and moisture and sap), and Earth (for soil, and solidity and toughness).
Relatedly, for the schools of magic, I like to see the following applied strictly.
Evocation means exactly the elemental "energies": Air (Thunder, Lightning), Fire (Fire, Radiant), Water (Cold), and "Elemental Chaos" Earth (in the form of Acid).
I look at
Illusion as the fifth element Ether, where it is force constructs that make illusions "quasi real" and objective. (Think Star Trek holodeck.) The kind of distortion that is subjective and relates manipulation of a creatures sensory experiences, is a Phantasm, and really belongs to the Enchantment school as mental effects with the Psychic damage type. Meanwhile force constructs like Arcane Armor, "spectral" Mage Hand, Mordenkainens Magnificent Mansion, but also Magic Missile, Shield, Reverse Gravity, Fly, and Telekinesis, can all belong to the Illusion school in the sense of the manipulation of Ethereal Force.
Transmutation is Earth magic. Spells that relate strictly to the Earth element include Mold Earth, Stone Shape, and similar. However, Transmutation extends to the creature types where its state of solidity imbues these life forms with matter. Thus, the Transmutation includes Earth, Plant, and Beast, plus Ooze as an early lifeform that both Plant and Beast evolve from. The Astral dominions of Arborea and Beastlands refer to the "life" of these lifeforms, Plant and Beast, respectively. But it is the element of Earth that refers to the "materiality" of these lifeforms. Earth (clay, stone, gems, metal), Plant (wood, cotton, linen, resin, foods), and sometimes Beast (leather, horn, ivory), together accomplish the fabrication of objects, equipment and structures. Likewise, they accomplish shapeshifting. While healing is part of the protective magic of Abjuration school, the activity of healing would be the Transmutation of the body of a Beast, knitting together in a Plant-like way.