Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
To clarify with the ability score and leveling, every level after first you get +1 any one ability score but at first level you get a +2 to any one ability score, correct?
You mention different bonus progressions of +6, +10, +15, and +20 but no +12, does this mean we will get different save progressions?
+12 is just the +10 progression, with an arbitrary +2 bonus at 1st level.
And that likely still will be in there.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
So people getting into very rapid fire (rapid shot + many shot or haste, never mind all 3) can't reload fast enough? I guess that puts a limit on the effectiveness of archery builds.
Whether Haste, Rapid Shot, or Manyshot add extra attacks in Corefinder remains to be seen, vs. adding extra dice or effectiveness or reducing/removing penalties for full attacks with ranged weapons. Permanent abilities that do that likely would also enhance the effect of the following swift action as part of their effects.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 2 people marked this as a favorite. |
Having said that, I don’t understand why it is an Action, and not an effect, which may be where the feat dysphoria is coming in...
I have no idea what "feat dysphoria" means, but I will say that a number of things that used to be feats in PF1 are just going to be things characters can do in CF without needing any feat-gating.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
‘Near Miss: When your attack misses (but is not a critical failure), while you fail to penetrate your target’s defenses you still wear them down with your onslaught. You deal nonlethal damage appropriate to the type of attack you were using to the target equal to one-half your Base Attack Bonus plus your Power Modifier. No other damage bonuses apply to a Near Miss.
You can use this action on an attack that misses due to the miss chance for concealment, as long as you are attacking the target’s actual square.’
I’m all for opening up stuff that is currently gated off by feats. But this one seems like it’s a bit too much, and should remain in the realm of a feat...
I know you’re playing with how far to push out what is a freely-available move. But this one may be a bridge too far...
We will see how people like it as an idea. I'd rather put out interesting new ideas to try that are still within the spirit and conceptual map of Pathfinder 1E than be entirely risk-averse and just be doing an editing job on it.
It's in there both to play with expectations and possibilities, and as another potential use for your swift action. It's certainly a far less effective thing to do than a standard action, but it's a little something extra to do in certain cases.
It does require a regular (non-crit) failure, so a flock of kobolds missing you by a mile isn't going to do anything to you. It is explicitly nonlethal damage so it's not going to kill you immediately.
But it does still present the potential of very tough creatures not being able to ABSOLUTELY ignore weaker creatures, while also giving PC martials a bit of a fallback option if they're fighting a tough bad guy. There are some similar things built into combat maneuvers, where even if the maneuver doesn't succeed fully you may still accomplish something useful with it.
There also is some thought being noised around on the magic side about similar "minor benefit even on a failure" effects.
As to whether it stays in final... we shall see...
| 1 person marked this as a favorite. |
It depends on what they change, I am not happy about perception not being a skill and if they get rid of skill points, that would be a no sale for me. But just will have to wait and see.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 3 people marked this as a favorite. |
It depends on what they change, I am not happy about perception not being a skill and if they get rid of skill points, that would be a no sale for me. But just will have to wait and see.
Skill points will still be there.
Perception in CF is going the way of Concentration in the 3.5 > PF1 transition. It's a thing that is virtually mandatory for everyone to max out, so just make it a uniform characteristic for everyone and let them invest their skill points where they like.
Yes and now that it isn't a skill you can't use skill focus, skilled kineticist(greater), etc. for it now.
| 3 people marked this as a favorite. |
Yes and now that it isn't a skill you can't use skill focus, skilled kineticist(greater), etc. for it now.
That doesn't necessarily mean there won't be ways to improve Perception. Also, since there has to be some GM arbitration in converting any previous edition, it's entirely reasonable that if a class ability etc would have allowed improving Perception that a GM allows it to continue to do so in CF even if it's not a skill.
From what I've seen so far, CF does not feel like a nerf at all. If anything, the richness of new options are a power increase... though so far that's aimed at martial types and general activity.
I'd register my concern (as you've done) and sit back and see what shakes out over time, 'cuz so far things have been impressive, IMHO.
| 2 people marked this as a favorite. |
Is it possible in the Corefinder game to make low monsters a stronger threat to higher level characters? Please, nobody tell me to shut up and play 5e. :) I'm curious if there could be optional rules to make this happen.
| 5 people marked this as a favorite. |
I just caught up to the publicly available blog posts about the different action types, and my general impression is that while there's some good cleanup going on, there seems to be a solid chunk of additional complexity being added to rules that are already plenty complex. Especially, this is additional rules complexity added at a baseline level.
Anything that lies at the baseline level (ie. stuff that every 1st level character can do) provides another rules element that a new player potentially needs to know about - or at least be aware of when they're determining what to do on their turn. Every time I've thought about how to clean up 1E's base rules, my inclination has been to trim, not add.
Things adding complexity:
| 2 people marked this as a favorite. |
Unrelated to complexity:
Do recovery saves really allow you to shed any non-permanent condition in a few rounds? So anything that inflicts 1 hour of sickened or shaken or something similar no longer functions as a long-duration debuff?
The text for recovery saves says that Effects with no saving throw allow you to attempt a recovery save with an additional -5 penalty... but the rules don't give you a DC to roll against in such circumstances.
| 1 person marked this as a favorite. |
I don't remember where it was posted but someone came up with the idea that the dazzle condition should be a 20% chance miss instead of the -1 to attack rolls. I really like that idea.
I do agree that some things have been made more complex then needed but I still like the patrol full action thing.
The best way(s) to make low level monsters more dangerous is...
Class levels
Templates
Increased numbers
Smarter tactics
Use environment
Magic items
Spells
Strong allies
Powerful mounts
Also low level monsters are low level for a reason;)
| 3 people marked this as a favorite. |
Having said that, I don’t understand why it is an Action, and not an effect, which may be where the feat dysphoria is coming in...I have no idea what "feat dysphoria" means, but I will say that a number of things that used to be feats in PF1 are just going to be things characters can do in CF without needing any feat-gating.
Confusion as to why/whether things should be a feat or not.
My main point is that Near Miss as quoted by SunKing appears to be an Action, where to me it looks like a resultant effect, and not something a character should tacitly need to decide to do, or even be able to do.
They fired, they almost missed. It strains my incredulity that a character could use an Action to stop an actual miss from missing by doing...something after they have fired and the missile is en route, to create a near miss. I mean, RPG combat is abstract and all, but this seems to break immersion for me.
So this isn’t about feats at all. I’m all for not having feats to do things anyone should be able to do (Power Attack, Weapon Finesse) but this is different - more about whether Near Miss is an Action or not.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 2 people marked this as a favorite. |
I just caught up to the publicly available blog posts about the different action types, and my general impression is that while there's some good cleanup going on, there seems to be a solid chunk of additional complexity being added to rules that are already plenty complex. Especially, this is additional rules complexity added at a baseline level.
Anything that lies at the baseline level (ie. stuff that every 1st level character can do) provides another rules element that a new player potentially needs to know about - or at least be aware of when they're determining what to do on their turn. Every time I've thought about how to clean up 1E's base rules, my inclination has been to trim, not add.
Thanks for the feedback and thoughtful comments! We've obviously gone somewhat the other direction with Corefinder Alpha, with the intention of collecting and clarifying scattered, fuzzy, and often hidden rules in PFRPG in a clear, explicit, and concise manner, as well as providing rules for cases that have come up at tables but have no clear answers in the PF1 rules.
As to your specific thoughts, see replies below!
Recovery Saves are a full action, except they aren't if you don't have enough actions to take them.
The wording was tough here. The idea of being able to shake off was that you could "take a round" to try to clear your head and end an effect on you, but because some PF effects prevent you from acting (or force you to use your actions for other things, like running away), there needed to be some way to work those in.
It might be easier to just make it "not an action" that happens at the end of your turn.
The DC they ask you to hit changes every round.
It does indeed, to make it progressively easier to recover from something the longer it goes on.
Has rules for what qualifies as an "effect" (A poison doesn't count, but presumably a spell with the poison descriptor that sickens for 1 hour does?)
You'd think language like that wouldn't be necessary, but I've seen too many message board arguments about things like "being dead doesn't prevent you from taking actions because [insert eyeroll-inducing reason]" and other goofiness that we just figured we'd clarify as much as possible exactly what you can and can't "recover" from - specifically calling out *damage* vs. *effects*.
Kneeling as a state, rather than simplifying down to just standing and prone. Also, special rules for standing from chairs.
This rule already exists in PFRPG. It's just buried in the fine print of Table 8-6: Armor Class Modifiers (p. 195) and explained nowhere else.
Reloading rules. Why do I need a swift action for reloading in a special way, a use action to reload the same weapon in a simple way, and a full action to reload a different class of weapons? (Why isn't this just: light ranged weapons are reloaded as part of firing them, heavy ranged weapons are reloaded as a full action?)
It's an attempt to codify all ranged weapon reloads to work the same, rather than having bows have different rules from slings which are different from hand/light crossbows from heavy crossbows from pistols from rifles with even more variation depending on which ammunition you use.
Streamlining six kinds of reloading special cases to three (light, heavy, and light with full attack).
Quick search vs. search. Adding low value tactical complexity in exchange for rules complexity. "Player: The wizard went invisible? I want to listen to see if I can hear where they are. GM: OK, is that a quick search, search, or extended area search?"
"What kind of action does it take to look for someone/something that's hidden?" In PFRPG it's variously either a standard action, a move action, or a free action, depending on the cases in which it's being used.
CF streamlines this to make Search a Use action for 10 feet (or a Swift action for 5 feet).
If you really want to focus on searching, you can trade a move for a Use to double your range, or trade a Standard for a Move for another Use to extend your search twice and triple it. Pathfinder is about levers to pull and fiddly bits, so being able to decide how much effort you want to put into searching seems like a useful slider bar for players to use.
If it turns out in playtest that this amount of granularity is more trouble than it's worth, it's certainly something to change, but for now we like the idea of spelling out exactly what kind of action you use to search for things (and let you choose which action to use for it).
Splitting move actions into move and use actions, simply because they're now another resource for players to track on their turn. "Can I do something useful with my use action this turn?" is something I expect to slow down combat.
It might. Some of the change there was to make the came more transparent to people learning the game, wherein lots of things that didn't seem to have anything to do with movement were called "move" actions. For clarity of language, we've leaned heavily into making move actions be movement-related.
Likewise, some of the things that are now listed as use actions in CF are things that were kind of buried in a variety of special case combo actions in PFRPG. We've disaggregated them to be their own category of actions that, like move actions, now say what they do and do what they say - a "use" action is about using an object in some minor but still important action. Others are about defining things I've seen come up at the table and have heard reports about from other tables about things that come up and cause confusion or frustration at the table (like what kind of action is needed to pass an object to another character).
But you might well be right. People might get stuck and obsess over maximizing every possible action. Playtest will reveal a lot.
Actions with subactions (like the the Advance move action), which introduce more decision points.
This action already exists in PFRPG, it's just called "If you have a base attack bonus of +1 or higher and move more than 10 feet, you can draw a weapon as a free action as part of your movement." (and cue endless argument threads about whether you can or should be able to draw a wand, rod, potion, or any other item in its place)
Things like Pull Up, which have unique Attack of Opportunity rules, and require an ability check (with variable DC).
Much like the use actions before, Pull Up, Grab On, and similar actions were codified to provide a tangible and explicit rule for things that GMs had to kind of kludge together in PFRPG. GMs still could, of course, but the project is not solely about streamlining the PFRPG rules; it's also about clarifying codifying things that were only loosely defined in the rules, buried or scattered across various supplements, or not addressed at all.
Whether and how one PC can pick up another and what that means for both the PC picking them up and the PC being picked up are kind of a mess in PFRPG (Can you do it with a grapple or drag combat maneuver (standard action)? Is it like picking up an object (move action)? Does it provoke for either character? Does it encumber either character? If you pick up a creature and then drop them do they fall back prone? How many hands does it take?). Corefinder aims to clarify messy rules like that, and the Pull Up action answers all relevant questions in 96 words.
One other important and intentional design goal is to work more ways into the rules for PCs to help each other. In the case of Pull Up, it essentially allows a standing PC to use their action to help an ally up, while simultaneously taking the AoO hit for getting them up from prone.
On one hand, sure, it's added complexity in terms of options, but anyone playing PF has already made their peace to a large extent with playing a system that has a surfeit of options. Corefinder aims to make it clearer and easier to understand what those options are and to present as many of them as possible in a single core section that is easy to reference and get the answers you need quickly and effectively.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 1 person marked this as a favorite. |
Unrelated to complexity:
Do recovery saves really allow you to shed any non-permanent condition in a few rounds? So anything that inflicts 1 hour of sickened or shaken or something similar no longer functions as a long-duration debuff?
Yes. If it's not instantaneous/permanent, then you can shake it off.
The text for recovery saves says that Effects with no saving throw allow you to attempt a recovery save with an additional -5 penalty... but the rules don't give you a DC to roll against in such circumstances.
The target number for DCs are contained within the effects or abilities themselves. The rules here tell you how to do saving throws, etc. A giant spider's poison will have its DC, a pit trap its DC, a spell its DC, etc.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
Yes and now that it isn't a skill you can't use skill focus, skilled kineticist(greater), etc. for it now.That doesn't necessarily mean there won't be ways to improve Perception. Also, since there has to be some GM arbitration in converting any previous edition, it's entirely reasonable that if a class ability etc would have allowed improving Perception that a GM allows it to continue to do so in CF even if it's not a skill.
Correct.
From what I've seen so far, CF does not feel like a nerf at all. If anything, the richness of new options are a power increase... though so far that's aimed at martial types and general activity.
That is intentional. Things like swift actions and immediate/reactions started out largely as the purview of spellcasters and certain specialized class features. We've built in more options accessible to everyone, especially martial characters, and worked to clarify a lot of actions that lots of characters might want to be able to do, in what we hope is a clear and concise way.
I'd register my concern (as you've done) and sit back and see what shakes out over time, 'cuz so far things have been impressive, IMHO.
Thanks for the kind words. Glad you are enjoying.
Freehold DM, you are just as old as the rest of us;)
It would be nice if magic armor added it's enhancement bonus to your saves or at least a flat bonus in general. I was never a fan of cloaks of resistance, it never made sense that cloaks would be the item to improve saves when armor and vest made more sense. Plus there are lot of fun magical cloaks that you can't get because saves are more important. Though I would be fine if the base saves were improved instead.
| 1 person marked this as a favorite. |
You are very close to convincing me to patronize you, just to be able to access the materials sooner. And, even though I probably won't be able to play test it live, I believe that I will want to read it once you have gotten things to that stage.
I like the clarity. I like the consolidation. Keep it up!
| 1 person marked this as a favorite. |
I have stuff I have been working on for a while for my home game/campaign setting that was looking at 3.x as a base with a lot of modification. Some similar things are seen here with pathfinder, great minds and all. I may become a patron.
| 2 people marked this as a favorite. |
I can't wait to get to combat maneuvers and other combat options. I wonder what feats will no linger be feats.
| 2 people marked this as a favorite. |
Is it possible in the Corefinder game to make low monsters a stronger threat to higher level characters? Please, nobody tell me to shut up and play 5e. :) I'm curious if there could be optional rules to make this happen.It’s a sad state of affairs when you have to preemptively ward off those who are going to tell you to go ahead and play 5e...
Yeah, it is. :)
|
| 1 person marked this as a favorite. |
I can't wait to get to combat maneuvers and other combat options. I wonder what feats will no linger be feats.
Well I can tell you that feats to not take AOOs for combat maneuvers as well as power attack/deadly aim/combat expertise aren't around anymore. There's a few more I can't remember off the top of my head.
But what about feats that add bonuses to(and vs) combat maneuvers?
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
But what about feats that add bonuses to(and vs) combat maneuvers?
Most (but not necessarily all) feats that are "just math" are getting eliminated, made into things that anyone can do rather than requiring a feat, folded together with other feats, or otherwise revised.
More feats are also being built to scale and improve with level.
Wait, your not getting rid of Cunning, Dodge, Fleet, Great Fortitude, Improved Initiative, Iron Will, Lighting Reflexes, Skill Focus, and/or Toughness?
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 3 people marked this as a favorite. |
Check out all the updates on our Patreon blog for the Corefinder Project, dedicated to revising, streamlining, enhancing, and hopefully perfecting the Pathfinder RPG 1st Edition rules into a fantastic core system with modular support for multiple genres!
Corefinder Design Digest #16: You've Gotta Move
Corefinder Design Digest #17: Hidden Speeds
Corefinder Design Digest #18: Immediate Opportunity
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
Wait, your not getting rid of Cunning, Dodge, Fleet, Great Fortitude, Improved Initiative, Iron Will, Lighting Reflexes, Skill Focus, and/or Toughness?
The feats chapter is being worked on right now, so nothing is final (to the extent that ANYTHING in CF Alpha is *final*), but I'll reiterate what I said above:
Most (but not necessarily all) feats that are "just math" are getting eliminated, made into things that anyone can do rather than requiring a feat, folded together with other feats, or otherwise revised.
More feats are also being built to scale and improve with level.
Precisely that that means for the specific feats you listed remains to be seen once we get in the turnovers and developed versions of the feats chapter.
AoOs are a reaction, and you get one reaction at the start of combat, and it refreshes only if you spend a swift action. Do I have that right?
Help along can move someone smaller than you 15' which is difficult to do if you can't move at the same time. Only along a diagonal from one side of you to another, barring reach. Can you move at the same time?
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
AoOs are a reaction, and you get one reaction at the start of combat, and it refreshes only if you spend a swift action. Do I have that right?
That's one of the optional rule ideas we put in there. It's the same fundamental mechanic as already exists in PFRPG (i.e., when you take an immediate action, it uses your swift action for your next turn), just making it something you can choose whether or not to do. That is, you could choose to use your swift action for something else and then not have your reaction recharge.
Various classes and creatures will get extra reactions that they can use for specific things, like martials getting extra AoO reactions. The base rules here are the uniform mechanics that everyone can use all the time.
Help along can move someone smaller than you 15' which is difficult to do if you can't move at the same time. Only along a diagonal from one side of you to another, barring reach. Can you move at the same time?
One way to envision it is as you moving along with them (like them leaning on your shoulder as you helped them limp forward or pulled them out of the muck or whatever), but it also can be pulling someone up to, into, and through your space (or alongside it) including a diagonal as you mentioned. As written, we've gone with the latter, but it's certainly something we could tinker with as we go.
I take it we will get more reaction options through class features and feats, correct?
Will we get the same number of feats (based on level and class) that we had before?
Will you give race and skill based feats actual race and skill type/subtype like combat, item creation, metamagic, etc.?
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
| 3 people marked this as a favorite. |
I take it we will get more reaction options through class features and feats, correct?
Yes.
Will we get the same number of feats (based on level and class) that we had before?
Possibly more. And each individual feat slot will be worth more, because many things that were entire feat chains in PF1 are being condensed into single feats and/or scaling feats that increase in power with your character.
Will you give race and skill based feats actual race and skill type/subtype like combat, item creation, metamagic, etc.?
Entirely possible. Not yet set in stone.
So when is the next rules preview?
Wow, this one has been a ghost town since Thanksgiving.
Are you guys still going to have traits and/or favored class bonuses?
Will we get max HP per level up instead of rolling or using average+1?
Will you change when spontaneous casters get higher level spells to match the rate that wizards, clerics, etc. do?
Will you change how many spells known that spontaneous casters get and/or how many spells a class can cast in general?
What about cantrips for 4th level casters?
I would like to see some skills that you get for free...
Maybe a rule that you pic 2-4 skills(craft, knowledge, perform, and/or, profession) that you get free ranks in.
Another idea is some skills that a class would get for free like divine casters getting knowledge religion, sorcerers getting their bloodline skill, casters getting spellcraft, cavaliers getting ride, etc.
|
Contributor, RPG Superstar 2008 Top 4, Legendary Games
|
So when is the next rules preview?
I believe #22 is the last one to have gone live, then I took a break posting new stuff until after Thanksgiving. #23 should go public this Friday or Saturday.
There's gonna be a rapid-fire blitz coming, though. I believe Patrons are already on #27.
|
|
| 1 person marked this as a favorite. |
Wow, this one has been a ghost town since Thanksgiving.
Are you guys still going to have traits and/or favored class bonuses?
Will we get max HP per level up instead of rolling or using average+1?
Will you change when spontaneous casters get higher level spells to match the rate that wizards, clerics, etc. do?
Will you change how many spells known that spontaneous casters get and/or how many spells a class can cast in general?
What about cantrips for 4th level casters?
I would like to see some skills that you get for free...
Maybe a rule that you pic 2-4 skills(craft, knowledge, perform, and/or, profession) that you get free ranks in.
Another idea is some skills that a class would get for free like divine casters getting knowledge religion, sorcerers getting their bloodline skill, casters getting spellcraft, cavaliers getting ride, etc.
Traits and FCBs are in rough territory due to not being as needed. I'd say we're more likely to keep traits than FCBs, but nothing's set in stone yet.
I'm a fan of max HP per level myself, so I'll probably push for that.
Yeah, they almost certainly will.
That's also something we're considering.
Considering ninja is a 4th level caster with cantrips, it's likely.
Too be honest I would fine with no traits if all skills are class skills or at least it is easy to get skills as class skills. As for favored class bonuses(FCB) the only ones I like are extra skill point, extra hit point, and extra spell known. If there are other ways of getting those I would be fine. Though if we get max HP per level then we wouldn't need the extra hit point FCB. If every class has more skill points then you will not need the extra skill point FCB. Also if you have better spell known progression, you wouldn't need extra spell known FCB, plus every race would benefit, not just humans.
Will you still be using CMD? I would love just to use AC.
Will you alter any of the classes weapon and armor prof.?
Will there be good unarmored options for some or even most classes?
Some examples would be.
Force Armor(SU)- constant mage armor effect that increases as you level. +4AC at 1st plus additional +1 at 3rd and every 4 levels after that. Good for arcane and psychic based classes.
Monk-like AC- Using stat mod for AC plus the dodge bonuses at 4th and every 4 levels after. Would love to see Barbarian, Brawler, and Kineticist getting con mod. Other classes using Int, Wis, or Cha. This would be good for most classes that use armor. It would be nice if Monks and Shifters could choose their primary stat for AC(and other class abilities).
Natural Armor- Having high enough natural armor that they don't need armor(and can't use it in general). Maybe starting with a +5 to +7 natural armor bonus that increases with level. this would be more race based then class.
I would love to see options like these that don't need an archetype, just as a character creation option.
I always liked the idea of "nature magic" and felt that Druids, Hunters, and Rangers should use that instead of divine. So is there any chance of you guys using such a concept?
If so will there be different casting components like psychic magic gets?
Will you be changing how wands, staves, and other charge based magic items work and/or who can use them?
| 2 people marked this as a favorite. |
Can we make it a rule that a natural 20 is always a hit even bypassing things like cover, mirror image, displacement, blur, and similar effects?
Can we bring back called shots? I would love to be able sever tentacles, eye stalks, hydra heads(more easily), etc. strike vulnerable places on an armored enemy, construct, etc. and other tricks.
A rule that wooden stakes can bypass a vampire's DR would be nice.
| 3 people marked this as a favorite. |
Can we make it a rule that a natural 20 is always a hit even bypassing things like cover, mirror image, displacement, blur, and similar effects?
I'd rather not see that. 5% is - in my opinion - way too frequent to have it negate a bunch of defenses. Worse, it'd be extra insulting that not only did your attacker get lucky and bypass your defenses, but you're also probably taking critical damage.
Can we bring back called shots? I would love to be able sever tentacles, eye stalks, hydra heads(more easily), etc. strike vulnerable places on an armored enemy, construct, etc. and other tricks.
A rule that wooden stakes can bypass a vampire's DR would be nice.
Now I could get behind those two.
|
Can we bring back called shots? I would love to be able sever tentacles, eye stalks, hydra heads(more easily), etc. strike vulnerable places on an armored enemy, construct, etc. and other tricks.Please, no. From a player side, I am sure this looks all kinds of attractive, but on the DM side, it feels way too much of a [expletive] move to use it against the players, but, it has to cut both ways or it is just power gaming. Perhaps, it would be better that certain iconic creatures have a special rule in their entry, such as the hydra, that allows for such fancy maneuvers or the lopping off of excessive limbs?
Something like the 'broken' rules for items, carried over to body parts, could be an option. Damage it once with a called shot, and it's got a -2 to rolls made with it until healed by any old healing. Damage it again, and it's out of commission until repaired by a lesser restoration type spell? The exact amount of damage to reach those thresholds would vary (so attempting to 'sunder' the Tarrasque's bite might be more trouble than it's worth. 'Yay! I did 20% of it's hit points in one blow and now it has a -2 to bite me?' :)