Spellcasting Gone Wrong [PEACH] [3.5]

[Ajadea]

There's all this fluff about Sorcerers losing control of their powers in their backstory. Yet this doesn't seem to happen to any other class, and the whole idea of them ever losing that control is unsupported.

So here's an idea I had, drawing from Frenzied Berserker's Frenzy Mechanic.

For this world, spellcasting is harder. A spellcaster needs a Casting Stat modifier of Spell Level -1 to cast a spell, and the modifier cannot be negative, or the 'caster' cannot in fact cast anything (So, 26 in their Casting Stat by level 17). Mind you, this is actually not unreasonable: Base Stat 16, +4 from stat increases, +6 Item of Stat +6.

This is a world where a spellcaster has to be exceptional to survive without kinda blowing themselves up in the process. The spellcaster who does hit exceptional can go on to break the world horribly. This has been accounted for in the game-world's history and is not only expected, but actively feared and worked against.

MAD casting has been removed: the caster determines DC and extra spell slots with the same stat that they use to determine if they can cast the spell. This means that Archivist casts solely off Intelligence (or would if I was including it as a viable class in-game), Spirit Shaman casts off Wisdom, and Favored Soul casts off Charisma, etcetera.

So, without further delay, my idea.
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Every time a spellcaster who has access to spell levels they cannot cast is hit for an amount of damage greater than their casting stat, they must make a Caster Level Check with DC (10+Damage Taken)*(Combined Total of Spell Levels they are unable to cast) or automatically unleash a burst with radius Y of raw magic that deals Xd10 damage to all things within the burst (the caster included) where X is their Caster Level and Y is their Casting Stat modifier. No Save, No SR. It bypasses all DR and regeneration, even Epic DR or a Tarrasque's regeneration. Those killed come back as Skeletons, Zombies, or Shadows, and the caster, if they die, comes back as a ghost under the DM's control.

Well, why can't a normal caster do that? I can think of reasons upon reasons why they wouldn't, but what if they think they have to?

So, as an immediate action upon being damaged for a sufficient amount, they can expend spell slots to release a burst of raw magic with radius Y that deals Zd10 damage, where Y is the Casting Stat modifier and Z is the total amount of spell levels expended, which cannot exceed the Caster Level of the caster. No save, but SR does apply. Like in the above situation, the caster takes an equal amount of damage and the dead become undead.

Is it unclear? Is it unbalanced?
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EDIT: Okay, apparently I not only missed a key point I was trying to make, the whole thing was woefully unclear.

Trigger: Caster (with access to spell levels they can't cast) gets by a single attack that deals more damage than their Casting Stat
Result: Unleashes a burst effect with radius (casting stat modifier) that deals damage equal to (CL)d10.

[Rainbownaga]

Let me clarify, if a spellcaster has access to spells that they cannot cast, they risk exploding if they try to cast them?

As you said yourself, this is fairly unlikely to be of much detriment since the more min-maxed casters will have high primary casting abilities anyway. What you're mostly doing is preventing poorly rolled characters to become casters and giving min-maxers an extra option.

[Ajadea]

Wait, what? Wait, did I delete part of the description?....yeah, sorry.

What I meant is that if they have access to spell levels they cannot cast, then every time they take damage greater than their casting stat modifier, they risk blowing themselves, their party, and everything else up.

[Epsilon Rose]

I have to agree with Rainbow. This probably won't effect a min-maxed character and is just going to punish people for having balanced stats.

Also, is there a reason that the at will burst has sr but the I explode burst doesn't?
Also also what units are the distances in? Feat, five foot squares, miles, parsecs?
And lastly you do realize that either option is liable to be more fatal to the caster than anything else, right?

[Ajadea]

I have to agree with Rainbow. This probably won't effect a min-maxed character and is just going to punish people for having balanced stats.

Also, is there a reason that the at will burst has sr but the I explode burst doesn't?
Also also what units are the distances in? Feet, five foot squares, miles, parsecs?
And lastly you do realize that either option is liable to be more fatal to the caster than anything else, right?

15 to 16 is 2 points (point buy) of difference. Perhaps we don't have the same idea of balanced; to me, 16, 14, 13, 10, 10, 8 isn't that much different when compared to 15, 14, 13, 12, 10, 8.

The intentional explosion is still different from the accidental explosion. Mindset, circumstance, etc. Magic responds to things like that.

Radius is measured in units of 5 foot squares.

Yeah, I'm aware of that.

[Epsilon Rose]

Sorry, when I said balanced I meant internally balance (eg not 8,8,8,30,8,8).
I'm not talking about how many points you get to spend but how you spend them. Your spell casting rules encourage favoring one stat to the extreme so you don't kill your self, which will result in both stronger spell casting (since there going all in) and less believable characters. Where as a system that encouraged you to spend points on other abilities would make for more realistic characters and (marginally) weaker casting.