Well, the system isn't designed to defend against poor character design.
Then what is it good for? Seriously.
The
advantage of a level-based system is that you can guaranty that people will have a minimum and maximum level of diversity and power, and that characters will advance in a roughly comparable fashion over time. The disadvantage, of course, is that things are extremely pixilated, the power jumps are potentialy quite extreme, and there are by definition some pieces of severe shoe-horning going on.
If you make a level-based system in which the minimum
or maximum in diversity
or power is not there - then the
difference in diversity and power (which is the only measure of game balance there is), is not capped. You have made a level-based system with no advantages at all.
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Practically speaking, your spell-seeds system suffers from the fact that low level spells are still sucky at high levels. Caster levels still act as a "you must be this tall to enter" when facing SR. People who don't play the game exactly right don't matter in the grand scheme of things.
And the way to play things exactly right is to max out your spell seeds so that you have a pile of spells that will be useful at your level. The way to play the game wrong is to take even a single level of a non-spellcasting class ever in your life. The way to play the game wrong is to invest in cross-class spell seeds or diversify your spell seeds beyond what you can maintain at maximum level. People who play the game wrong will find themselves making less difference at high levels than the henchmen of the henchmen of the other PCs.
Your system introduces the following "pseudo-choices":
* Playing a Wizard/Rogue
* Taking spells that are not on your list
* Splitting your Research up between a bunch of schools of magic.
These choices look like they are legitimate, but they are not. While taking 2 Rogue levels and losing 2 caster levels might not seem so bad, by the time you are a 40th level Wizard/Rogue you'll be short 10 levels of SR penetration and your spells won't even scratch enemies of your level. In an infinitely advancing system, any proportional hit to power is always a bad deal.
And the same with taking cross-class spells. Or diversifying spell seed expenditures. Sure it might look OK to be one level behind at the beginning, but by level 10, that's five levels behind. Your henchman's henchman is only four levels behind.
D&D math, and your math, is based upon an inherently exponential power curve. 2 levels of effect is supposed to be euqual to double the power. If you fall behind the curve by 2 levels, you're half as powerful. If you fall behind the curve by one level every other level, or every four levels even - you're going to become increasingly relatively behind. First you're half as good, then you're a quarter as good, then you're an eighth as good....
You can't fit the model of "put a bonus anywhere you want" into the model of "you get better every level". It doesn't work. That's why the magic items are broken. That's why the Fighter is extremly sucky. That combined model does not function.
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On going Skill Based:
If you wanted to go skill-based, and drop all pretenses of levels entirely, that would be worakble. If you wanted to continue to use the d20 as a starting point, that would also be workable.
Here's a skeleton I've been working on:
The rule of Four: You can't have any of your active skills be more than four points higher than any of your other active skills. You can't have any of your stats be more than four higher than any of your other stats. When you gain a stat point or a skill point, you can raise any of your stats or skills by one, but you still can't raise any of your stats or skills to more than four more than any other. So if you have a Strength of 8 and a Charisma of 4, and you got 2 stat points, you could put one into each or two into Charisma. If your Strength and Charisma were both 6 and you got 2 stat points you could put them in any way you wanted. Knowledge skills are not subject to this limitation.
There is an entire chunk of backstory that explains how this works in-game, so in the final result it's probably not going to seem all that contrived. Primarily it's in there to keep the game from disolving into one-shot kills or endless slap-fights as skill-based systems are wont to do.
Actions and DCs: In order to perform an action, there is a DC. You roll a d20, add your appropriate skill, add your appropriate stat, and add any appropriate circumstantial modifiers. If you meet the DC, you succeed. For every two points you beat the DC by, you succeed more.
Levels of success make opposed rolls inherently much easier to deal with. Allowing the stats to explicitly float makes a lot of the headaches go away. It's one of the few really good ideas to come out of Vampire.
Abilities and Skills: Every ability will have a
research requirement, and a
skill requirement. So learning how to use a Guisarme would require a certain amount of time practicing with a Guisarme and a certain minimum melee skill. Higher skills would cut research times down, but would not remove the research prerequisite (you would still need a Guisarme or the Liber Igni or whatever to get the ability you wanted, it would just take less time).
This form of ability rationing allows people to achieve level-appropriate powers over time. It also allows the DM to give spot-bonuses to PCs by throwing in available research into more powerful abilities for characters who are lagging.
Damage and Death: When Bob attacks Jane with a chainsaw (or fireblast, or whatever), he rolls to-hit. The stat used to hit is also the stat used to dodge. Every effect level on the to-hit roll adds to the damage DC. If Jane is struck, she attempts to resist damage, and the stat used to damage is also the stat to resist. So it's Dex vs. Dex and then Strength vs. Strength. Or Int vs. Int and then Charisma vs. Charisma. Every effect level you generate is a point of damage, and every character can take 10 points of damage before going down (and another 10 before being mostly dead, and another 10 before being alldead).
This is an important balance point, because it means that a "balanced" character - that is one who splits stats and skills evenly - is tough on the defense and light on the offense. A character who is min/maxxed - that is one who puts everything allowed into swording or magicing or whatever - is tough on the offense and light on the defense. But the degree to which this is true is numerically identical in all ways.
Which active skills there needs to be is up in the air. It's hard for me to decide because it's not important to game balance in any way.
-Username17