3) Cantrips should have a large but finite casting limit (say, 20/day), to allow for combat use but preventing logical abuses of being cast hundreds of times a day.
This thought from TwoSix on page 2.... wow, that jumped into my head as such an amazing and simple thing. Easy too: 1 cantrip per day, per point of the associated stat (so, 16 to 20) - multiclass casters use the lowest stat. (For just a touch more, add proficiency bonus, so it's like 18 to 26? so the casters taking feats still get a
little progression over time.) But this way the casters will need to spend their spell slots during a long day, not hoard them all for the "boss fight" while just pew-pewing their 2d10 damage through the rest of the dungeon.
(combats in my game are more "8-12 rounds" than the white room web conversations that toss around "3 rounds of combat" examples. so two fights in, you're out of cantrips! In fact, I would love to see a mechanic similar to many Class Abilities, where casters are starting to think "Is it worth sacking a spell slot, so I can get one more use of this cantrip??")
Honestly, though, I would be easily convinced to go the other extreme -- cantrips are unlimited but never more powerful (or only fractionally stronger).
Firebolt is still doing 1d10 in the archmage's hands, that's
why he learned more powerful spells! He still doesn't need to carry a heavy crossbow, but he's gonna tap you with a
lightning bolt not a
lightning lure.
Per the OP's question though, 32 pages ago... My answer for "what should magic be able to accomplish" is "depends on the campaign". Previous campaign, the PCs were planes-hopping, friends with planetars, and summoning elder deities for Q&A sessions. This campaign,
dimension door is the most powerful spell in the party's hands - and their foes (mostly) have nothing more powerful than
fly or
fireball. [Exceptions abound, both "low spells w/upcasting" and the ogre mage's
cone of cold.] Because that's the campaign feel we wanted.
As a baseline, though, I think magic should get more dangerous and/or more difficult as the spells get more powerful. I don't want fledgling wizards growing tentacles or causing explosions of pink posies just because they cast
mage armor for the day. But maybe - like
Event Horizon (the movie) -
teleport and
plane shift come with some risk?
Conjure X sometimes ends with the critters breaking free of control (like the
old conjure elemental spell!) and rampaging until put down? Anyone remember the Midkemia novels, and the mage who always had fresh fruit? He didn't conjure it, he was actually (magically) stealing it from a specific merchant's fruit stall... maybe that merchant gets fed up and hires some adventurers to find the thief!
Also, I absolutely prefer THEMATIC RESTRICTIONS (aka "specializations"), which previous editions had, and many people on this thread have mentioned. For all Casters! While the Necromancer uses necromancy, and maybe strays a little into enchantment (killing someone's will) and evocation (some "directed necrotic energy" spells)... the Cleric of the Moon has a lot of handy "night" and "light" based spells, curing and commanding insanity, and is great against lycanthropes. But while she's great against the enchanter, she's the wrong match against the Necromancer, because Moon magic just doesn't have anti-undead powers. The evoker can be a direct damage dealer, but a specialized "elementalist" will have more options. Tim the Evoker can blast you with fire, ice, or even concentrated pummeling blasts of air, but you need an "elementalist (fire)" to create a
wall of fire or
fire shield.
Without going through the entire spell list and rebalancing every spell, you can quickly establish thematic limits. Something like "Necromancers have full access [level 1 to 9] to necromantic spells, medium access [level 1 to 3] to enchantment, medium themed access to evocation, conjuration, and divination (i.e. conjure undead, but not all conjuring;
spirit bolt for necrotic damage; ask a spirit of the owner to
identify his item, but can't just walk up to a magic device and suss it out), and restricted access (level 1 to 3, but costs +2 spell slots) to any other wizard spell". "Clerics of the Moon have full access to all Moon-domain spells, major access (level 1 to 6) to all other spells in the Moon goddess's other domains, and restricted access to all other cleric spells."
At
great effort, I would try building a "magical physics" rules engine that was internally consistent, and roughly balanced with martial capabilities. "Level 1 spells can manipulate 2 pounds of force, plus 1 per proficiency bonus" - enough to hit with moderate power, or create 3 "pounds" of fire, or cast haste on your familiar. Fire is the most damaging element (for example, no value judgement), which is why fire spells are so common... "a pound of fire does about 2-3 damage, while a pound of lightning is (always 1) up to 4 damage, but unreliable". So the cantrip is going to do about 4-6 fire damage or 1-8 lightning, while a 1st level spell will cause a blast of 8 to 12 fire damage (or a fan of it, doing 4-6 over a wide area); 1st level lightning does 1 to 16 damage, and refuses to become "AoE" at such low amounts. [Obviously, this is where you say "go play something other than D&D"!]
Just one, the Wizard (Arcanist).
