As others have noted later in the thread, while handling power scaling is A reason that a campaign might falter, its more the minority. The simple truth is, high level campaigns usually take a lot of IRL time. Campaigns die by attrition, or because the campaign is resolved successfully earlier, or because the group wants to do something else....those factors are a lot more prevalent than "high levels is difficult to run".If we want games to go to 20, more often, then there needs to be 3 major changes:
1) Power grading for classes needs to be brought in-line. Quadratic power increase for spellcasters needs to be brought down which mostly means getting rid of some "Classic" spells that we all know are broken.
2) Classes need to be restructured to gain interesting options every level. A5e has been decent about this, with social and exploration features added to every class providing new or more certain ways to get around obstacles that don't require someone to cast a spell.
3) NPC scaling needs to be reined in, hard. Yes. A dragon isn't much of a challenge as a solo opponent when the party can collectively drop 300 damage in two rounds or less. So address the output issue and stop inflating enemy health and damage to ridiculous numbers to try and compensate.
Taking in this data, the thing that is always interesting to see is how much time is spent on forums just like this debating levels that don't exist for 95% of games. 11th level is basically 20th for most groups, a level maybe you get to once in a blue moon, and its more of a "maybe one day" fantasy.
How often optimizers discuss 6th level spells and high level abilities....but they simply don't matter to the common zeitgeist of the game. Caster vs Martial discussion often talks about high level games....which don't exist in large quantities.
Really what the data shows is....this is a 10th level game, not a 20th level one. Basically 11-20th might as well be the epic level handbook for all intensive purposes. Our discussions should focus almost exclusively on 10th level and lower, and leave the high level for that "crazy once in a blue moon kind of gaming"
I have a distinct memory of one of my friends playing a monk/sorcerer of some sort and having planned their career quite far in advance. At one point he said "Just wait until level 11, then things will really kick in." (I believe because of a feat or PRC feature that allowed them to use Charisma instead of Wisdom for their monk AC bonus).Yeah I'm thinking if this stat was similar back in the day all those XYZ 5/PrC2/PrC1/PrC3 type builds were essentially theory crafting.
this is main way to see higher levels.My groups pretty routinely get into the high teens, but we usually start a little higher and level up pretty frequently. (Every 2-4 sessions.)
one fine solution is to remove all 6+ level spells from the game.If we want games to go to 20, more often, then there needs to be 3 major changes:
1) Power grading for classes needs to be brought in-line. Quadratic power increase for spellcasters needs to be brought down which mostly means getting rid of some "Classic" spells that we all know are broken.
Unfortunately, I can't game design more hours into the day or days into the week in the real world. The only solutions I can offer have to be within the confines of the game itself.As others have noted later in the thread, while handling power scaling is A reason that a campaign might falter, its more the minority. The simple truth is, high level campaigns usually take a lot of IRL time. Campaigns die by attrition, or because the campaign is resolved successfully earlier, or because the group wants to do something else....those factors are a lot more prevalent than "high levels is difficult to run".
So while you could certainly do some work to clean up high levels, its not going to result in a significant increase in high level campaigns.
Personally... I'd just keep 6th level spells as the 'high end', myself, if you're going that direction. It's the last level where the scaling still makes sense with spells like Chain Lightning or Sunbeam.one fine solution is to remove all 6+ level spells from the game.
you can keep uscasting if you want or not,
maybe some iconic 6th level spells can be moved to 5th level,
Arcane gate, Create undead, Mass suggestion, Harm, Heal, Summon fiend True seeing are all good 6th level candidates to be moved down to 5th level with some reduction in power, duration, range or other things.
if there is no upacsting, the higher level slots can be turned into lower level ones:
View attachment 412525
or just use Spell-Points(SP) to save some hassle.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.