Help me with overchanneling

[tedcahill2]

I'm still working on my kinda sorta non-vancian casting system (http://www.giantitp.com/forums/showthread.php?525920-non-vancian-ish-casting-system) but I am getting totally stuck on the rules for overchanneling.

I plan to roughly half the spells per day each class can cast, with no bonus spells per day from high stat modifiers, but counter that fact by implementing overchanneling rules, which allow casters to continue using spells after they run out of spells slots. Primary casting stat modifiers will be implemented to allow easier overchanneling.

Here's what I know so far:

+ I want overchanneling to require a check of some sort, my working idea is that you roll a d20 and add your caster level and primary casting stat modifier to it. DC 10 + spell level x 3?

+ Succeeding the caster check means the spell casts as normal, failure means it does not cast.

+ Whether the caster check succeeded or failed you will be negatively affected by the overchannel.

I'm open to suggestions on all three of those points, but where I'm really stuck is on the negative impacts of overchanneling.

I know that I want failure to cause fatigue/exhaustion. I know that I want it to stunt your spell casting by an increasingly long time depending on how much overchanneling you're doing. I know I want it to cause damage in some form.

I also can't decide how to determine the impact of overchanneling. I thought about tying it to fortitude saves, but that gives a pretty big advantage to clerics and the like with high fort. I thought about having your caster check, and how close you were to the overchannel DC, to determine the impact, but wasn't sure I wanted that one check to impact both the casting and the overchannel effects.

Help!

[The_Jette]

Are you planning on giving the casters a way to mitigate the overchanneling? Normally, I'd discourage that, but since you're halving their spells and taking away bonus slots, it seems like mitigation should be encouraged. Have you considered the idea of making the overchanneling a concentration check, then the CL check would be to mitigate? Like, roll to bring the spell back to your mind, then roll your CL to see if you can keep the energies from damaging you too much? Or vice versa, really. For instance:
Concentration DC 10+2*SL = Spell Cast
CL DC 10+3*SL = 1/2 damage from spell or damage is subdual instead
Damage for overchannel = 1d4 * SL damage (possibly subdual)

[tedcahill2]

Are you planning on giving the casters a way to mitigate the overchanneling? Normally, I'd discourage that, but since you're halving their spells and taking away bonus slots, it seems like mitigation should be encouraged. Have you considered the idea of making the overchanneling a concentration check, then the CL check would be to mitigate? Like, roll to bring the spell back to your mind, then roll your CL to see if you can keep the energies from damaging you too much? Or vice versa, really. For instance:
Concentration DC 10+2*SL = Spell Cast
CL DC 10+3*SL = 1/2 damage from spell or damage is subdual instead
Damage for overchannel = 1d4 * SL damage (possibly subdual)

I'm not opposed to it, but I was trying to avoid using a skill because A) skill bonuses can be boosted pretty easily and B) even though casters already have plenty of reasons to put ranks in Concentration I didn't want to make it a must have skill for the entire alternate casting system.

It also doesn't totally make sense because my channeling system, and the remaining spell slots casters have, remove the fire and forget fluff from vancian systems. Instead, all of my casters will cast spells spontaneously, although I have come up with numerous ways in which each class will build their list of known spells.

Channeling a spell differs slightly from the traditional magic system in that you are not simply manipulating magic energies. Instead, what all casters are doing is using their bodies and minds as a conduit for magic energy. By allowing this energy to pass through them they are able to manipulate it's properties to produce the desired effect (i.e. the spell). Casters never lose the ability to manipulate magic energy, but the act of moving it through yourself is taxing. The spells per day that each class has represents the number of times they can safely channel magic energy through themselves without risking overchanneling. The idea with channeling like this isn't that casters have a limit on the magic they can use in a day, like a battery, which is a niche that psionics covers. Higher level spells require more energy to pass through in a single casting that low level spells, so while higher level spell slots can be consumed to cast lower level spells, lower level spell slots can't be used to cast higher level spells because the body simply can't handle that much power all at once, even if it could otherwise safely cast numerous other lower level spells.

So anyway, I think I rambled a bit, but it's not about recalling the cast spell to memory, it's about resisting the effects of channeling magic energy to many times in a day.

At the same time I don't want casters to go all day either. While I'm not setting a hard limit on spells per day, I want the rules of overchanneling to eventually knock out careless casters.

As far as mitigating the affects entirely yes, I will consider it, but I was thinking of making the DC for resisting overchanneling effects somehow cumulative so that the more a caster does it the more likely they are to see more severe consequences.

[martixy]

Look at this: http://www.d20pfsrd.com/magic/variant-magic-rules/active-spellcasting-variant-rules/
...and spell blights.

[Gildedragon]

I'd say Spellcraft Check (15+Spell Level at least) to see if cast or not
+ Fort Save to check for backlash / mishap

This way one can cast and get no backlash
Cast and take backlash
Flub the spell and take no backlash (from trying to handle too much magic)
Flub the spell and take no backlash

Though this discussion is better suited to the Homebrew subforum

[tedcahill2]

I'd say Spellcraft Check (15+Spell Level at least) to see if cast or not
+ Fort Save to check for backlash / mishap

This way one can cast and get no backlash
Cast and take backlash
Flub the spell and take no backlash (from trying to handle too much magic)
Flub the spell and take no backlash
If you used those parameters wouldn't you expect divine casters like clerics and druids to have an easier time overchanneling. They have spellcraft as a class skill and high fortitude saves. That provides them a pretty unfair advantage compared to most arcane casters, that lack a good fort save.

I chose caster level because it is a direct correlation to the experience of a caster. Rangers/Paladins having an effective caster level of 1/2 their class level is a good example of why caster level is a good starting point to determine ones ability to overchannel.

What I'm struggling with is how to determine the severity of the damage/effects of overchanneling.

[Gildedragon]

If the overchannel DC is Spell Level based then failure ranges is probably best.
Each range has some associated mishap...

Maybe a base damage based on Spell Level (SL * 2 points of damage)
+
A mishap? The possibility of Spell having a paradoxical effect from being mishandled is a useful idea?

[tedcahill2]

If the overchannel DC is Spell Level based then failure ranges is probably best.
Each range has some associated mishap...

Maybe a base damage based on Spell Level (SL * 2 points of damage)
+
A mishap? The possibility of Spell having a paradoxical effect from being mishandled is a useful idea?

I want there to be a damaging factor for sure, but since this is for all casters I need to figure out a way that it doesn't favor one class over another. That's been one of my major struggles.

Fort makes sense to resist the effects of overchanneling. Taking hit point damage (lethal or not) make sense for one of the effects of overchanneling.

Both of those things, which make perfect logical sense, strongly favor casters with good fort saves and higher HD. In other words, clerics and druids become better able to overchannel spells than wizards and sorcerers.

[The_Jette]

I want there to be a damaging factor for sure, but since this is for all casters I need to figure out a way that it doesn't favor one class over another. That's been one of my major struggles.

Fort makes sense to resist the effects of overchanneling. Taking hit point damage (lethal or not) make sense for one of the effects of overchanneling.

Both of those things, which make perfect logical sense, strongly favor casters with good fort saves and higher HD. In other words, clerics and druids become better able to overchannel spells than wizards and sorcerers.

You could give Sorcs and Wizards a certain number of spell levels that they can overchannel for "free" so to speak. Like, at level 1, they have 1 spell level that they can over channel before they start taking damage for overchanneling, like their level. It gives them a little bit of flexibility.

[tedcahill2]

You could give Sorcs and Wizards a certain number of spell levels that they can overchannel for "free" so to speak. Like, at level 1, they have 1 spell level that they can over channel before they start taking damage for overchanneling, like their level. It gives them a little bit of flexibility.

A classes spells per day is basically representing the number of spells they can channel safely in a day. Overchanneling is what happens when you run out of your spells per day.

Your suggestion could work though, if I understand it right. Give the classes with high HD and fort fewer spells per day, forcing them into overchanneling sooner? Classes like wizard and sorcerer would be hit harder by overchanneling, but have more safe spells per day.

I'm going to keep thinking on it.

[daremetoidareyo]

I would make negative metamagic feats and stack them on spells until they sputter.

Minimize spell
Half area spell
Half duration spell.
Weak Spellcaster level spell.(-4 caster level )

Each spell after slots run out adds one of those negative metamagic to the spell effect.