I tend to jump around in design, partly to keep everything in balance / hold the bigger picture, and partly because I get exhausted with just focusing on one thing.
So...Wizards!
A conceit of the dark high fantasy setting of Elderblade is that a Warrior, an Expert, and a Spellcaster are about evenly matched. What does that mean? They all can contribute in fun ways to every "mode" of e game, whether combat, exploration. a chase, a heist, a negotiation, an infiltration mission, whatever. They are not equal in all these areas, but neither are they horribly outmatched; a player will never be left twiddling his thumbs when outside of their class' specialty, or afraid to contribute for fear of hurting the team.
Wizards in Elderblade don't just cast "fireball." They are rigorously trained students of the Elder Tongue, part of an arcane society that operates parallel to the mundane society of kings and vassals. When a wizard casts a spell, they draw on great traditions of their forebears and master wizards of the day. A wizard casts "Melcantor's Explosive Fireball"!
Mechanically, I am reorganizing spells into Schools of Magic which involve rigorous training either at an institution or via apprenticeship. These schools include the traditional 8, but also anything you could add -mancy to the end of (e.g. oneiromancy = dream magic). Each school has a Cantrip which can be used for free (no fatigue) by anyone with proficiency in the school. Each school has 3 levels of proficiency: Trained, Expert, and Master. Casting spells is fatiguing (this is not Vancian magic), using a system similar to Blue Rose/True20 and a Fatigue Track similar to Star Wars Saga Edition...still working out exact details but probably will be a Constitution, Charisma, or Wisdom check (Player's choice, or maybe depends on school of magic) vs DC 12 to avoid fatigue. The DC may need calibration to account for casting easier or harder spells, not sure yet....
Wizards have a core feature called
Schools of Magic which grants them Trained rank in a school of their choice at 1st level. At levels 3, 5, 7, and 9, the wizard learns another school at Trained rank. At levels 13, 15, 17, and 19, a wizard learns a school at the Trained rank or advances a school already trained in to Expert rank. At levels 23, 25, 27, and 29, a wizard learns a school at the Trained rank, or advances a trained school to Expert, or an Expert school to Master. Specialties and Paragon Paths will add a couple extra schools on top of these. Right now I'm thinking when a Izard gets a proficiency rank in a school they record all school spells from that rank in their spellbook (meaning they can cast them using the fatigue rules).
As an example, here are the Abjuration school and the Fire school in abbreviated form:
Abjuration
CANTRIP: Resist Natural Hazard
TRAINED: Protection Spell (authorship contested, merges all the Protection from... spells)
TRAINED: Helena Sucumvort's Arcane Ward (merges Arcane Lock and Alarm)
TRAINED: Dietmar Ritterfeld's Marvelous Shield
EXPERT: Saher Afram al-Zulys' Field of Repulsion
EXPERT: Umqvist's Dimensional Anchor
MASTER: Grigori Pacostyev's Banishment
MASTER: Helena Sucumvort's Mind Block
Fire (Pyromancy)
CANTRIP: Extinguish / Ignite
TRAINED: Gout of Flame (authorship contested, basically Burning Hands)
TRAINED: Arric Belgadris' Flaming Sphere
EXPERT: Fierna du Tarqinia's Fireshield
EXPERT: Melcantor's Explosive Fireball
EXPERT: Arric Belgadris' Wall of Shimmering Flames
MASTER: Fierna du Tarqinia's Incendiary Cloud
MASTER: Meteor Swarm of Archmage Orvad cep Alsayeez
For example, a 13th level wizard might be designed thus: Fire (Expert), Abjuration (Trained), Anti-Magic (Trained), Enchantment (Trained), Force (Trained). There would also probably be 1-2 more based on their selection of Specialty and Legendary Path.
It is a very themed way to look at a wizard, one which requires a choice between breadth and depth. Also, it lines up nicely with Fighting Styles, Rogue Tricks, Barbarian Rage Powers, Monastic Disciplines, and other class features that mirror the progression of Schools of Magic...this makes multi- or split- classing much easier to implement.