CMB DC, why 15 plus target CMB?


Combat & Magic


I really like the rules for the Combat Maneuver Bonus. But, why use 15 + target’s CMB? Why not 10?

If two people roll a d20, 50% of the time you will roll higher than your opponent. Why not have the DC be 10 + modifiers? If you do it this way, it still relies on one roll and has the same odds as standard v3.5. Having a DC of 15 + always favors the defender.

Paizo Employee Director of Game Design

Having it be 15 + CMB does indeed favor the defender. I do not feel that performing a Combat Manuever against a foe should be a 50% chance as this would make it a frequently better option that just attacking. While this does not matter much for Bull Rush, Grapple can be a severe hindrance.

Jason Bulmahn
Lead Designer


Jason Bulmahn wrote:

Having it be 15 + CMB does indeed favor the defender. I do not feel that performing a Combat Manuever against a foe should be a 50% chance as this would make it a frequently better option that just attacking. While this does not matter much for Bull Rush, Grapple can be a severe hindrance.

Jason Bulmahn
Lead Designer

Fair enough! Advantage to the attacker. With grapple, it should be more difficult to hold someone than to get away. Regardless, in a grapple, the role of attacker and defender alternate. So, it seems to balance out.


Jason Bulmahn wrote:

Having it be 15 + CMB does indeed favor the defender. I do not feel that performing a Combat Manuever against a foe should be a 50% chance as this would make it a frequently better option that just attacking. While this does not matter much for Bull Rush, Grapple can be a severe hindrance.

Jason Bulmahn
Lead Designer

I'd like to continue this one.

If grapple is the real reason for making it 15 instead of 10, haven't you already "fixed" grapple (for the better, I might add) with the different levels of held/grabbed/grappled/pinned? Achieving the equivalent of a 3.5 grapple has been raised by +10.

Another argument in favor of 10, as opposed to 15, is that people who like opposed rolls retain the option of using them without changing the balance of the game.

Finally, I note that the Escape Artist DC for breaking a grapple remains 10+CMB.


Adventure Path Charter Subscriber; Pathfinder Adventure Subscriber

How do the various monsters who have 'Improved Grab' as a special ability interact with the new grapple? As soon as they grab someone they can no longer damage them. I think the new grapple should allow unarmed damage also. (or at least the Improved Grab special ability should allow it).


Why not opposed rolls instead of a fixed 15? With a fixed DC you can easily get into a situation whereby you cannot do a special attack no matter what the case. Opposed rolls do not add that much complexity and give you a chance to have a hail mary


Adventure Path Charter Subscriber; Pathfinder Adventure Subscriber

Thinking about it some more, the 15+CMB DC may be too much in favor of the defender. In my 3.5 games, PCs already rarely take advantage of combat manuevers and with the increased difficulty I can't see any of them being worth attempting.

While grappling can be very powerful, it becomes extremely difficult under the alpha rules due to the higher starting DC and the fact that you have to beat the DCs by 5 or 10 to really get good results.

Bull rush is ridiculously underpowered with the higher DC. A base 30% chance (15 or higher) to move someone backwards? I can't think of many instances this would be better than attacking.

Tripping is barely better. You give up an attack to get a 30% chance to trip someone and the benefits of having your opponent prone aren't all that great. So you get an AoO when they stand up...you could have just attacked them in the first place. If it's something weak like a spellcaster, well they can just as easily disentegrate you while lying on the ground as standing up - all they have to do is make a skill check to cast. The only factor that made tripping powerful with the 3.5 rules was the improved trip feat where you gained a free attack when you tripped your opponent.

Disarming is a manuever that may work under these rules, but I would keep the +4 bonus for Improved Disarm instead of reducing it to +2.

A DC of 10 + CMB would be fine and then maybe you'd see PCs attempt the manuevers once in awhile.


TabulaRasa wrote:
Why not opposed rolls instead of a fixed 15? With a fixed DC you can easily get into a situation whereby you cannot do a special attack no matter what the case. Opposed rolls do not add that much complexity and give you a chance to have a hail mary

Using the standard DC of 15+CMB, you still have a 5% chance of succeeding (rolling a 20).

When two people roll dice is essentially each is setting the DC for the other. Having one roll with the defenders DC at 10 would be basically the same. However, a DC of 15 substantially favors the defender. DC 10 seems more appropriate to me, especially considering the changes made to grapple.


Statistically, a DC 10 favors the attacker slightly; the average for a d20 is 10.5. If you're going to change it, I would be more in favor of 13+CMB. This puts it in the "not an easy option" range, but doable. If someone specializes in it (i.e. Improved Trip, Improved Disarm, etc.), the DC goes down to 11+CMB... or about the average of a roll.

I'd prefer not going back to an opposed roll, for a few reasons. One, it's more time consuming. Two, randomness favors the NPCs drastically. It favors the less skilled (who are usually the NPCs) and those who are exposed to fewer rolls (who are always the NPCs). If you have a random roll, individual NPCs benefit a lot more than PCs.


I am opposed to setting a fixed DC for the CMB, as it makes it too difficult to succeed against Large creatures.

For example: Joe is a 10th level fighter with a 22 Str, and for some reason he wants to wrestle a brown bear. This act of heroism should be possible in a fantasy game. However, the base DC is 15 + 8 (str) + 4 (bab) + 4 (size) for a total of 31. Joe needs to roll a 15 on the die just to get a grab. Going out of his way to take Improved Grab only earns him a measly 10% increase in sucess rate.

At least with opposed rolls he could get lucky, which simulates battlefield conditions. Really, we should be making opposed rolls for all defenses, but that would just be too time consuming. I think allowing them for special rules is ok. Besides, since when does the speed of game mechanics drive their design? What about suspense? Drama? If I wanted fast game mechanics I would play a CRPG.

The Exchange

The opposed roll is a bad choice and always has been. With this DC 15 set, even if it favors the defender, it quickens the games. I also have used a monster with improved grab in a playtest already but I tested out another aspect of if the creature succeeds on it's Grapple check, it automatically deals it's damage. The creature was not ever going to be able to pin the creature but why would an Ankheg pin an opponent it's trying to drag away to eat. As Jason as pointed out in another thread, the old system and a DC 10 always favors the attacker. If that Ankheg would have used the older system, he probably would have still succeeded but left the Defender with no option to escape. Some numbers to show this. +11 is the normal Grapple for an Ankheg but most opposing rolls at that level are really low(around -3 to +6) The creature has a +5 advantage. With the new System the Ankheg's CMB is +8 and the PC's around a DC 15 to 21. It isn't going to always succeed. Now I understand that this is grapple but other monters have these types of bonuses and higher to Bull Rush or Trip. So if the PC's have a little more defence against them, they atleast have a chance unlike before.


Adventure Path Charter Subscriber; Pathfinder Adventure Subscriber
fliprushman wrote:
The opposed roll is a bad choice and always has been. With this DC 15 set, even if it favors the defender, it quickens the games. I also have used a monster with improved grab in a playtest already but I tested out another aspect of if the creature succeeds on it's Grapple check, it automatically deals it's damage. The creature was not ever going to be able to pin the creature but why would an Ankheg pin an opponent it's trying to drag away to eat. As Jason as pointed out in another thread, the old system and a DC 10 always favors the attacker. If that Ankheg would have used the older system, he probably would have still succeeded but left the Defender with no option to escape. Some numbers to show this. +11 is the normal Grapple for an Ankheg but most opposing rolls at that level are really low(around -3 to +6) The creature has a +5 advantage. With the new System the Ankheg's CMB is +8 and the PC's around a DC 15 to 21. It isn't going to always succeed. Now I understand that this is grapple but other monters have these types of bonuses and higher to Bull Rush or Trip. So if the PC's have a little more defence against them, they atleast have a chance unlike before.

Yes, but what about a player using these manuevers? If an ankheg can't grapple a human how is a human supposed to grapple another human?

The Exchange

What you are talking depends on that human's class. If it's two fighters, grappling/disarming/Bull rush should be hard to do since they are trained to fight each other off. If it's a fighter versus a wizard, the wizard still has a 50/50 chance of being grappled/disarmed/bull rushed by this fighter because he is not in heavy armor and should have a bit more movement. Now add in the feat bonuses, that wizard is toast. you begin to look at a 25% or less chance of that wizard being grappled. Strength being the deciding factor in that one. Most Wizards don't put points into strength so of course they should be easier to grapple/disarm/bull rush. Take this example versus the Ankheg, it's a larger creature so Bull Rushing it is not easy. It's CMB DC would 23 and a Human Fighter, Str 15, at that level would have a CMB of +5. That can go up to a +7 with a charge and, with a feat, +11 But the point is that an Ankheg should not be easy to move. It has more feet on the ground and the size difference.


Adventure Path Charter Subscriber; Pathfinder Adventure Subscriber
fliprushman wrote:
What you are talking depends on that human's class. If it's two fighters, grappling/disarming/Bull rush should be hard to do since they are trained to fight each other off. If it's a fighter versus a wizard, the wizard still has a 50/50 chance of being grappled/disarmed/bull rushed by this fighter because he is not in heavy armor and should have a bit more movement. Now add in the feat bonuses, that wizard is toast. you begin to look at a 25% or less chance of that wizard being grappled. Strength being the deciding factor in that one. Most Wizards don't put points into strength so of course they should be easier to grapple/disarm/bull rush. Take this example versus the Ankheg, it's a larger creature so Bull Rushing it is not easy. It's CMB DC would 23 and a Human Fighter, Str 15, at that level would have a CMB of +5. That can go up to a +7 with a charge and, with a feat, +11 But the point is that an Ankheg should not be easy to move. It has more feet on the ground and the size difference.

Yes, even in the ideal position of being a human fighter versus a wizard the fighter only has a 50% chance of grappling (or maybe a 60% chance if the fighter takes a feat to specialize in grappling). That's just horrible considering the rest of alpha grapple rules. If the fighter succeeds all he does is prevent the wizard from moving - the wizard can still cast a spell and blast him unless he succeeds by 10 or more! Now, as a fighter why would I try to grapple a wizard under those rules instead of just splitting him in half with my sword?

It's really the same with a fighter in combat with another fighter. The odds here are only 30% that a grapple will succeed which prevents movement, but allows that figher to pummel me with his weapons (and a 5% chance of grabbing the enemy so he has to pummel me with a 1 handed weapon instead of his greatsword). Why even attempt it and waste your action?

The Exchange

I can give you an example that would help you visualize it better.

Dwarf Fighter Str 15 Lvl 1.
vs.
Elf Wizard Str. 10 Lvl 1.

CMB for the Dwarf Fighter: +3
CMB for the Elf Wizard: +0

Dwarf tries a maneuver: 1d20+3 vs. DC 15
Dwarf has to roll between a 12 and 16 to get a basic success and a 17 to 20 for the next step. Now if the dwarf wants to keep his weapon in hand, he gets a -4 to his grapple check. Now he has to roll a 16 to 20 to succeed but can use AoO's against the Wizard.

But you must remember that this is 1st level and characters are not as good as they can be. So lets up the levels. I'm going to 10.

Dwarf Figheter 10 Str. 17
vs.
Elf Wizard 10 Str. 10

CMB for the Dwarf Fighter: +13
CMB for the Elf Wizard: +5

Dwarf Tries an maneuver: 1d20+13 vs. DC 20
Dwarf now only has to roll a 7 or better to succeed against this Wizard. He can now grapple this Wizard with a weapon with an 11. This wizard is now in trouble. Because if he is only grabbed, he still provokes AoO's with no chance of getting away.

Now these example take no account of magic or feats. Those will alter these numbers in favor of one or the other. But as a base line, this is what is looks like.

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