...or why you can't scale everything in a spell and still have level appropriate spellcasters.
On another page I recently came out against scaling spell DCs as the standard that all games should use. In truth I'm only really against scaling spell DCs with a spell system that already scales everything else, which was basically the case. So if I'd been feeling more like babbling, I would have added "Really though, I'm all about scaling DCs, but only if you're going to make everything else largely static to compensate." Why do I hold this stance? Well, here's your answer.
Premises and initial conclusions
There are three main premises I'm working from here, and you are welcome to disagree with and attack any of them you feel misguided:
- Spell power should derive more from spell level than caster level. Put another way, a spell of level X should always be more powerful than a spell of level X-1
- Spellcasters with the proper selection of spells have a CR equal to their level (at a minimum). Extended over all levels this means that standard CR math applies to them.
- Spellcasters derive almost all of their level appropriateness from their spells. This is true to such an extent that you can safely neglect any power gain from non-spell sources, even gear (which generally makes a PC over level appropriate anyway).
Taken together, these mean that the sum of their spell power needs scale in the same way as their CR does, and basically double every 2 levels. You can then sit down and do math on that sum to determine what sort of gap you need between the spell levels to make the CR math work out. At low levels you get that a higher level spell needs to be about 1.7ish times stronger than the level before, but that multiple converges to 2 pretty quickly. I just round to 2, since it's easier and the low level stuff is due to insufficient numbers of much lower level spells being available. If your spell levels have different multiples between them, you get weirdness where a spellcaster can deal with a greater or smaller number of equal CR encounters per day, which basically means they no longer have a CR that matches their level. It might be fine in a different system, but it's not particularly good as long as you're sticking with per day limitations (that's another rant).
Building from the conclussion
The WotC method of attempting to hit these marks (if it was even a conscious one) was to scale a bunch of stuff but have spell caps, area, and DC grow as a function of spell level. And it's ugly, but it sorta works. Spells of a higher level are partially more valuable because they are more likely to hit, partially because they hit more people, and partially because they might hit harder in some circumstances. This system is primarily aimed at blasting spells though, which isn't where the useful options often are.
The main problem with this method is that a lot of the time, a higher level spell is basically equivalent to a lower level one because of scaling or relevance. The issues of trying to fit linear scaling into an exponential growth system like CR should be familiar to most people here, and these issues show up all the time in spell design of this sort. In this already somewhat tenuous balancing act, removing the DC difference between levels just doesn't work, because what was often the only substantive difference between spells after scaling is now gone. You don't have a 2x difference between spell levels (if you ever really did in the first place) and lower level spells don't get left behind in the way that you need to maintain CR stability. You gain substantial net power, and are no longer CR appropriate.
My preferred solution to this problem is to actually scale DC (because it's an inverse attack roll and everyone else gets scaling attacks) and fix most of the other spell variables. If the DCs are the same for all of your spells, they drop out of the power equation. You can then set the spell effects to be 2x as good between spell levels, and don't have to deal with their built in scaling messing those numbers up.
You're letting some spells / spell levels become obsolete.
Sort of, but there's really nothing you can do to not obsolete some spells. It's less obvious in a scaling spell effect system because so much of it is riding on the non-scaling save DC, but it's there already anyway. If you accept my premises and conclusions, a level 5 spell is supposed to be 16× better than a level 1. That's either a huge area / number of targets or a boost in effect or duration or some combination thereof, and trying to make a level 1 combat spell matter in comparison to that is a fool's errand that will result in a net power change. It doesn't matter what system you adopt.
But obsoleting combat effects isn't even a big deal because there are other things that you can fill that slot with. Some counter / utility spells never really go out of style. Dropping the scaling from their companions in the spell level just decreases the excuses you have for not taking those spells, since the opportunity cost of preparing and casting those instead of something else is greatly reduced. It increases your versatility without increasing your combat usefulness.
The current spells don't actually follow that scaling, and attempting to do it would work out to an increase in spellcaster power.
Some already do, actually. Glitterdust -> Stinking Cloud is a 2x increase in area. Stinking Cloud -> Solid Fog is the same area but a removal of the save. These are each at least twice as strong as the previous one by my estimates. Fear is 3 spell levels above Cause Fear, and should be about 8 times stronger as a result. Panicked is about twice as good as frightened, and the increased area makes up the rest. The fact that plenty of other spells don't keep up with these spells suggests that there just aren't a lot of properly scaling spells.
This would make high level even more unworkable.
Possibly. It's not like anyone actually knows how the game is supposed to play over 12 anyway though. This at least provides solid benchmarks and power level references.
Blah blah wizard level blah blah...
Aside from my example spells above, this is actually balance level independent. If you want rogue level casters, you start off with rogue level powers and scale up from there. Same with fighter level or monk level, though in these cases you'd probably want to decrease the scaling since they don't scale with CR properly anyway. I choose wizard level starting points and examples because that's what I prefer (low wizard anyway), but if you wanted something else you would just build that.