Yaarel
🇮🇱 🇺🇦 He-Mage
Creating complex disparate mechanics, that combo unpredictably and level unevenly, will break the game. 1e, 2e, and 3e all failed because of disparate mechanics.The solution is to differientiate the spell lists (at the very least) and preferrably to have classes use magic in ways other than just casting spells.
Warlock Invocations is a perfect example. How about NO spells for warlocks, just a huge list of magic-like powers? Best if none of these simply mirror an actual spell.
I'm not saying I know right now how to do this, but frankly there are too many spellcasters.
How you get spells, what ability score is used, etc. is really just fluff IMO. I haven't kept up on new spells added since Xanathar's, but in the stuff I have, there are over 430 spells usable by the full-casters: Bard, Cleric, Druid, Sorcerer, Warlock, and Wizard.
Only 30% are unique to a single class, and over 40% are available to at least three full-casting classes!
I mean, really, how special can different classes feel if it comes down to:
I cast spells through music and song.
I cast spells given by the powers of my god(dess).
I cast spells provided by the force of nature.
I cast spells harnessed by the strength of my bloodline.
I cast spells bargained for with a mysterious entity.
I cast spells learned by toil and study of arcane secrets.
There is a disturbing trend IMO.
I know it isn't easy, and just calling different "powers" by different names isn't really what I mean.
Compared to 4e, 5e tries hard to diversify the mechanics. But only so much can be done before making the game unplayable.
That said.
Rituals need to be something separate from spells. Lean into fairytales and so on, where rituals can be anything, do anything, with any prereq. Rituals are more like a magic item treasure. Follow whatever instructions. Anyone can attempt to perform a ritual.