Note: this makes manuevers more complex and is not for the faint of heart
I have always found the way that CMB/CMD is calculated in PF seems rather limited in scope and always favors greater size and str compared to smaller, more mobile creatures. My solution to this was to split CMB/CMD into 3 categories based upon DEX/STR and the type of maneuver used.
For simplicity at the moment im calling them DCMB and SCMB, which are calculated as:
DCMB= BAB+DEX+Size(for DCMB I am reversing size so colossal creatures get a -8, and Fine get a +8)
SCMB= BAB+STR+Size(the regular scale)
DCMD=BAB+DEX+Size(the inverse scale)
SCMD=BAB+STR+Size(regular scale)
The following manuevers use SCMB only:
Bullrush
Sunder
Drag
The following manuevers use DCMB only:
Steal
Reposition (I was worried on this one going to sizes smaller than small but i think the fact that the creature has to get within the same square as their opponent in order to reach and attempt this balances it out just fine)
Dirty Trick
I also made a third category that can be used by either CMB to simulate the dual nature of how some of these could be used:
Grapple
Disarm
Trip
Overrun (if using DCMB, overrun would lose the option to knock an opponent prone)
Note: whichever CMB the person uses for these maneuvers, it would go against the highest CMD their opponent has.
Changes to feats:
I would make agile maneuvers allow a character to use their DCMB on all combat maneuver checks
Would need to add a feat to change all their combat maneuvers to using SCMB.
"Overpowering maneuvers" I dub thee.
Would also add a set of feats to add STR to DCMD or DEX to SCMD depending on which feat you took, or someone could take both of them to make their CMD return to what the current system uses. for names I guess they could be "Pillar of Strength" and "Leaf on the Wind" respectively.
Improved feats: the changes to these would be that the SCMB/DCMB usable CMs would have power attack OR combat expertise be their prerequisites, while the purely SCMB or purely DCMB ones would remain the same.
An example of how this might work out is as follows:
An ancient red dragon has the following stat block in normal play:
Str 39(+14), Dex 8(-1), Con 27, Int 20, Wis 21, Cha 20
Base Atk +25; CMB +43; CMD 52 (56 vs. trip)
The way I would change it would be:
Str 39, Dex 8, Con 27, Int 20, Wis 21, Cha 20
Base Atk +25; SCMB +43 DCMB +16; SCMD 53 DCMD 26 (+4 vs. trip)
I like the changes to the CMB but If the maneuver is always against the highest CMD then there should not be 2 CMDs.
I chose that way to make it so that size would not punish smaller creatures in dexterity based maneuvers, and so that it would not use both stats in calculation for creatures that have ridiculous DEX and STR if they want the benefit they can take the feats listed. Also should mention only the hybrid maneuvers are against the highest CMD, the dragon i posted above for example, would still be very prone to steal or dirty trick.
I'm thisclose to just scrapping the mechanic and making them simple opposed rolls.
Thats the thing though. Smaller creatures should and will have a harder time grappling, tripping, shoving, or otherwise incapacitating or moving creatures much larger than themselves.
Imagine a pixie trying to grapple a dragon. It looks ridiculous because it is. If the dragon sat there and did nothing the pixie still wouldn't be able to move it.
Ever have a stick thrown in front of your feet while moving about? and tripped on it? Was the stick bigger than you? Was it stronger? No, it was just a stick and you tripped on it using your own momentum as power. Martial artists apply these kinds of tactics against much larger opponents all the time.
As for grapple I did miss something and it could use clarification on what size scale it uses (i would go with regular scale), but even if you gave it the advantage of a size bonus a pixie could not beat the dragon's SCMD of 53(remember you use the higher CMD for dual stat maneuvers). In fact I am confident enough I will pull up a pixie's stats!
Pixie: Small size ( CMB/CMD will be listed as normal scale/Inverse scale for grappling purposes)
Str 7, Dex 21, Con 12, Int 16, Wis 15, Cha 16
Base Atk +2; SCMB -1/0, DCMB +7/+8; SCMD 9/10, DCMD 17/18
so even with a 20 pixie cant do crap to a dragon, not to mention he would take an AoO just to attempt it in which the dragon can do whatever combat maneuver to the pixie without even having to roll.
@Dungeonmastercal
Though what bonuses if any would you use? if it is a straight roll seems it would be unfair to those dragons getting grappled by pixies everywhere :P
First of all you haven't even clarified what dragon you're using, or their age. Second of all the point is no, after a level of size difference it doesn't matter how skilled you are. There are levels of difference in basic abilities that CANNOT be overcome with any measure of skill or training.
I guess my point is that disney lied. Not everything is possible if you try hard enough. That goes just as well for halflings, gnomes, goblins and everything smaller. They are going to have to become superhuman in strength or dexterity to match anything bigger than your basic trolls and other large size characters.
Ancient red dragon was the example, its the 3rd post in this thread. Aside from that I don't get the hostile disney reference, I said no such thing as a character with low stats being able to do anything, you are the one bringing that up. The point of this exercise was to make dexterity not as bad for combat maneuvers as it is now, and for size to have an interesting twist because no, size isn't everything with ALL combat maneuvers.
Either way I don't appreciate the tone of your posts.
Personally I find the rules as they are just fine.
If you want agility to count, Agile Maneuvers lets you use dex instead of strength. Both count defensively. Size is a mixed blessing, the bigger you are the more massive you are and so its harder to move you (and the easier it is to move another person), but then it's also harder for you to avoid maneuvers (remember, size AC penalties apply to CMD). Small size makes you harder to hit all around, but easier to throw around if you are hit.
That's pretty much as it should be, really.