Skill Based spell casting, Balancing

[Uber Dungeon]

I did mean spell level squared +10, that got jumbled up.
Danbu's first post gave me a good laugh, very quickly pointed out how fast someone would abuse said system.
I had considered that skill based casting would be a skill drain, and being spell craft based would suck for all other non INT based classes.
If I am to Continue with this idea it would probably be better to consider a caster level check Over a skill check.
So in mind that I am aware that letting my players look at 9th level spells, I can handle the imbalance this will bring to the game, My aim is to make it dangerous, while still having lower level spells reasonably within safety reach
So posing this as a Caster level check
(Hypothetical Numbers)
spell level-----DC------Non-leathle damage
0--------------8------------1
1st------------10----------1D4
2nd------------12----------1D6
3rd------------14----------1D8
4th------------16----------1D10
5th------------18----------2D6
6th------------20----------2D8
7th------------22----------2d10
8th------------24----------4D6
9th------------26----------4D8

I will probably include in the game Wands of +1 to +5 that would grant that bonus to the caster level check for the roll.

 

[Greenfield]

The class mixing abuse I described is unaffected by the change. True, they won't be throwing high level spells nearly as soon, but then neither will dedicated spell casters.

One point I glossed over: Many spells have effects defined by caster level, either for duration, specific effect, or dice of damage. My build presumes the use of trick to fake caster levels.

The system as now clarified says that nobody except epic level min-maxers will ever cast a spell above 6th level, unless the DM is particularly generous with skill boosting items.

Let's see... 20th level caster with 23 ranks in Spellcraft, a 26 Int for +8 and Skill Focus for another +3 will need to roll a 12 or better to throw a 6th level spell. (Target number 46).

A 7th level spell would call for a 59, a number that just isn't possible without either a really tweaky build or a hefty Skill Bonus item, or both.

Consider something with a bit less drastic a curve, perhaps 10 + ( Level x 3 ) A 13 for a 1st level spell isn't unreasonable. A 16 for 2nd is okay. A 19 for 3rd is achievable. 22 for 4th is also achievable. ... the 37 for 9th seems about right.

Okay, the low end is too easy, but the high end seems better.

Maybe 15 + (Level x 2)?

Work something like that and it won't scale out of sane reach. Go with geometric progression if you want to require spell casterin characters to be really dedicated to their art, and the players to be min-maxers.

But, whichever scale you use, tricked out characters with minimal levels in actual spell casting classes will be at least as effective as dedicated spell casters. The reason is implicit in your concept: You want to base it on skill, and the casting classes generally aren't the ones with huge skill counts.

 

[N'raac]

Again, the words say "squared" but the chart does not. As Greenfield notes, squared makes it pretty tough on anyone casting high level spells. 15+2*level means a L1 character with moderate INT - say 14 - and max spellcraft ranks has +6 at 1st level and a 50% chance to cast a L1 spell. If it will be practical for a character like this to cast spells at "their" level, the tweaked out Wizard with high INT and Skill Focus is going to find it pretty easy.

What happens to spontaneous casters like bards and sorcerers?

Seems like the characters will cast a lot of higher level, long duration spells - they have time to rest/cast Cure Minor Wounds to deal with any failed rolls, and even that modest character above can cast an L4 spell 10% of the time.

As Greenfield notes, I don't need more levels in my casting class to build my Spellcraft skill up. Why take, say, 0 levels of Wizard? 1 Wizard and 1 Cleric level let me access most spells in the game.

 

[BlackSeed_Vash]

Personally if I was going to use a system like this for casting, I would also keep their spells/day relevant by doing the following:

1) No checks need to cast a spell of appropriate level and less than the total max per day.
EX- A 4th level wizard can can 4-zero, 3-first and 2-second level spells without needing to make a check.

2) Every time a spell is cast outside of the class limit, the DC for the day is increased by spell level. In addition once the DC has been increased for the day, all spells that would normally not incur a check now do so; however they do not increase the DC.
EX- The above mentioned wizard casts has spent all his second level spells, casts 2 more (using the OP's chart) the 1st cast is a DC 12, the 2nd has a DC of 14. Should the wizard try to cast a fourth level spell latter on, he is looking at a DC 20 check. If later on, the wizard casts his 1st first level spell of the day, he'll need to make a DC 18 check, but the DC will not increase from first level spells until he cast 3 more that day.

3) Any spell more than twice the spell level the character can cast is lethal damage.
EX- Again, the 4th level wizard can safely cast up to fourth level spells with fear of killing himself. Failure of a fifth level spell or higher will be a serious risk of injury or death.

 

[Greenfield]

What happens to spontaneous casters like bards and sorcerers?

They disappear.

As noted, the difference between a Sorcerer and a Wizard is that one prepares a potentially wide variety of spells in his relatively small number of slots, and the other spontaneously casts his narrow selection of spells in a larger number of slots.

By eliminating preparation and spell slots, the major differences disappear. All that remains is that the Intelligence based caster has an edge, both in the number of skill points available, and in the Ability Bonus to the Spellcraft check.

Bards are the "Man without a country". They get a lot of skill points, so it's easier for them to keep Spellcraft maxed, compared to a Sorcerer, but they're still casting at a disadvantage.

Consider a new skill or skills: Arcane Mastery and Divine Mastery.

Arcane Mastery is used in the formula in place of Spell Craft, and can be either Intelligence or Charisma based. Divine Mastery is used for Divine spells, and is Wisdom Based.

Use that instead of Spellcraft and you've leveled the playing field a bit. Int based casters will still have more skill points to spend on it, but at least the system won't double that advantage.

Oh, and at that point the Bard becomes far more functional. They're still limited to spells on the Bard list, but their greater skill base gives them a strategic edge, and they don't have to dedicate Feats to fake a caster level for spell effects.

But no matter how you implement this, you'll have to completely rewrite huge portions of the system.