Customizing and Personalizing Spells WIP

Just a mish-mosh of things from the Dungeon Master's Guide and Tasha's stuck here for easy reference. A bit more of a ruling than a rule that gets overlooked.

Customizing Spells

Sometimes you want to play a certain theme, like your lightning and thunder slinging Thor fantasy, but you look at your spell list at cry because they're all fire spells. Rather than being boring and just shoehorning yourself to a life of fireball, we can just make adjustments to spells so that they fit your thematic.
  When a character learns a spell for the first time, they can change the damage to a similar damage type permanently. Mundane damage types are bludgeoning, piercing, and slashing. Elemental damage types are acid, cold, fire, lightning, poison, or thunder. Divine damage types are radiant and necrotic (and tossing psychic in here). Force is it's own "pure" damage.
 

Spell Damage

For any spell that deals damage, use the Spell Damage table to determine approximately how much damage is appropriate given the spell's level. The table assumes the spell deals half damage on a successful saving throw or a missed attack. If your spell doesn't deal damage on a successful save, you can increase the damage by 25 percent. You can use different damage dice than the ones in the table, provided that the average result is about the same. Doing so can add a little variety to the spell. For example, you could change a cantrip's damage from 1d10 (average 5.5) to 2d4 (average 5), reducing the maximum damage and making an average result more likely.  

Damage Type

   

Personalizing Spells

Copypasta from Tasha's

Just as every performer lends their art a personal flair and every warrior asserts their fighting styles through the lens of their own training, so too can a spellcaster use magic to express their individuality. Regardless of what type of spellcaster you're playing, you can customize the cosmetic effects of your character's spells. Perhaps you wish the effects of your caster's spells to appear in their favorite color, to suggest the training they received from a celestial mentor, or to exhibit their connection to a season of the year. The possibilities for how you might cosmetically customize your character's spells are endless. However, such alterations can't change the effects of a spell. They also can't make one spell seem like another—you can't, for example, make a magic missile look like a fireball.
  When customizing your spellcaster's magic, consider developing a theme—often, the broader and more versatile the better. You may describe your caster's magic whenever you wish, particularly when it makes an interesting addition to a story. You may also use it to reinforce other choices you've made for your character, like making a bard's spells tied more closely to their favored art form or a cleric's spells themed around their deity.
  For example, the fireball of a wizard with a fondness for storms might erupt to look like burning clouds or a burst of red lightning (without affecting the spell's damage type), while the same wizard's haste spell might limn the target in faint thunderheads.
  Alternatively, a cleric who serves a moon god might radiate faint moonlight around their hands when they cast cure wounds, or their shield of faith might surround the target with glimmering crescent moons.
  Further still, a druid could choose a cherry blossom theme for their magic, causing delicate branches and pink leaves to grow when they cast entangle or shillelagh, and their faerie fire spell could appear more like wind-tossed petals than flames.
  -TCE pg.116