Imp said:
UA's incantations, or something like them, for the really big effects - teleportations, communes, plane shifts, the sort of things magicians should be able to do, but not routinely.
To me, this is a point that can't be emphasized enough. Mind you, I don't think the current incantation system handles it well enough.
If you remove the immense, world-changing, campaign-style-changing effects - the domain of spells you would get at 'name level' in AD&D, and especially those that you would get BEYOND name level - from the 'regular' magic system based on PC level and make it to spells what artifacts are to magic items, you open up a ton of "lower-level" design space and get much closer to fantasy books and movies.
This is one of the main things I want from an encounter-based system (implicit or explicit) - removing the things that let you "go nova" in the first place.
If casting
meteor swarm, for example, requires a ritual that takes multiple minutes to perform, it's not going to win you a battle in a dungeon crawl no matter how powerful it is. In effect, this completely removes the
meteor swarm effect from game balance concerns - which also means you can leave it completely in the hands of the GM without him facing any unforseen imbalances elsewhere in the system. The same is true for pretty much all the hot-button high level spell effects.
It also allows you to load these powerful spells down with potential drawbacks, dangers and quirks - again without changing the day to day gameplay.
This leaves you free to explore new room in scaling spells from levels 1 to 20. Does
fireball need to become available at 5th or 6th level? Or is it something of a midrange 'capstone,' suitable for 9th or 10th level, with one or more additional tiers of spells between it and, say,
burning hands? Should damage spells continue to scale at 1 die per level or more, or, as the warlock's invocations, should the be brought down to 1/2 progression? As it stands, there's no way you can do this because compared to the existing 7th, 8th and 9th level spells, such damage spells would be completely useless (they're already close). If utility and status spells creep up in levels to fill the design space opened by making the existing capstone spells into rituals, you can look into changing spellcasters' in-battle abilities so they CAN'T "go nova" in the conventional sense.