# My problem with CMB

### Combat

Let me start out by saying I like CMB, I like the new mechanic.

However, after extensive playtesting I have discovered one problem that really needs to be addressed.

If someone's CMB is 6 or higher than yours you cannot succeed. That is a very small margin compared to the 19 in 3.5.

Some math:

3P

My CMB is 0 and my opponents is 6:

15 + 6 = 21
D20 + 0 = no use

(though I'm not sure if 20's always succeed on a CMB).

3.5

My grapple check is 0 and my opponents is 19.

1 + 19 = 20
D20 + 0 = 20 still a chance

There needs to be a way for that narrow margin of possibility to be widened.

Pathfinder Companion, Pathfinder Accessories, Pawns, Starfinder Adventure Path, Starfinder Roleplaying Game Subscriber; Pathfinder Roleplaying Game Charter Superscriber

CMB is essentially the following:

d20+Cmb_A vs 15+Cmb_D (A - attacker; D - defender)

in order for the attacker to win you need

d20+Cmb_A > 15+Cmb_D

which is

d20 - 15 > Cmb_D - Cmb_A

This mechanic scales well by level and accounts for class differences - which to your point there are cases where you shouldn't try! This makes sense, why would a wizard every try to grapple the tough melee opponent?

That said, I might be inclined to make a 20 always win, I'll have to think about that.

Cainus wrote:

Let me start out by saying I like CMB, I like the new mechanic.

However, after extensive playtesting I have discovered one problem that really needs to be addressed.

If someone's CMB is 6 or higher than yours you cannot succeed. That is a very small margin compared to the 19 in 3.5.

Some math:

3P

My CMB is 0 and my opponents is 6:

15 + 6 = 21
D20 + 0 = no use

(though I'm not sure if 20's always succeed on a CMB).

3.5

My grapple check is 0 and my opponents is 19.

1 + 19 = 20
D20 + 0 = 20 still a chance

There needs to be a way for that narrow margin of possibility to be widened.

I think the best way to solve the issue without making it really complicated is to just do opposing d20+CMB rolls, since the current system indicates that when you are trying to either trip, disarm, or bullrush your opponent they are always at the top of their game and you have to reach that level +5, which takes the dynamic nature of those manuevers out of play.

Pathfinder Companion, Pathfinder Accessories, Pawns, Starfinder Adventure Path, Starfinder Roleplaying Game Subscriber; Pathfinder Roleplaying Game Charter Superscriber

I guess I look at it in the same light as a wizard casting spells... Would Merlin cast hold person on a rival wizard? With a Will negates saving throw, I think not. He might cast it on Conan with more optimistic results...

Likewise, the first level cleric (BAB 0) is less likely to hit the full plate bad guy. The fighter with weapon focus is less concerned about missing.

It's all a numbers game. When it comes to combat maneuvers you need to be aware of your abilities and your opponents capabilities.

Cainus wrote:

Let me start out by saying I like CMB, I like the new mechanic.

However, after extensive playtesting I have discovered one problem that really needs to be addressed.

If someone's CMB is 6 or higher than yours you cannot succeed. That is a very small margin compared to the 19 in 3.5.

Some math:

3P

My CMB is 0 and my opponents is 6:

15 + 6 = 21
D20 + 0 = no use

(though I'm not sure if 20's always succeed on a CMB).

3.5

My grapple check is 0 and my opponents is 19.

1 + 19 = 20
D20 + 0 = 20 still a chance

There needs to be a way for that narrow margin of possibility to be widened.

I use the roll a 20 add 10, roll a 1 minus ten variant for all rolls. This still gives the impossible to hit, grapple, skill check a chance. Of course this is essentially the same as saying roll a 20 auto hit etc.... Unless the DC is so high where adding the ten would not even succeed, in that case the pc just couldn't do it, which is possible since some things you just cannot succeed at.

I actually prefer that maneuvers don't have the 5% chance of auto-success. For things like grappling, it gets pretty silly.

toyrobots wrote:
I actually prefer that maneuvers don't have the 5% chance of auto-success. For things like grappling, it gets pretty silly.

If you don't mind, elaborate as to why? I see combat maneuvers like grappling as just another combat action. The 5% chance to automatically ignore armor and defenses from a sword attack is not much different in my mind to someone getting a lucky grip on the huge warrior.

If you don't mind, elaborate as to why? I see combat maneuvers like grappling as just another combat action. The 5% chance to automatically ignore armor and defenses from a sword attack is not much different in my mind to someone getting a lucky grip on the huge warrior.

I tend to favor interactive results for 20s and 1s. A strict policy of auto-success tends to lead to house-cats occasionally tripping ogres. Making it not automatic is sort of a cover-my-own-rear GM defense, if I want to allow a lucky shot I allow it, but it isn't a right. You may disagree and that's fine.

If you really want to make CMB resolve more like standard attacks, you should throw in behind the Maneuver AC method, which I think is the best thing to come off the playtest boards. If Maneuvers are handled exactly as attacks are and the DC is just as AC, then wow(!) you have your auto-success rule again, and the numbers play closer to 3.5.

</shameless plug of a well-liked houserule>

PS - here is the currently agreed-upon Maneuver AC Rule:

Spoiler:

Maneuver AC = (Touch AC) + (CMB)
CMB = (Your Attack roll) + (Special Size Mod)

As you can see, this method is virtually identical to CMB, only it takes into account already calculated attack factors. Simply resolve all maneuvers as attack rolls with the above modifier (usually 0) vs. the maneuver AC.

The actual changes are two:

• Replace the arbitrary 15 from the maneuver DC with Touch AC.
• Replace CMB with a standard attack roll plus the Special size modifier from 3.5.

• DitheringFool wrote:

CMB is essentially the following:

d20+Cmb_A vs 15+Cmb_D (A - attacker; D - defender)

in order for the attacker to win you need

d20+Cmb_A > 15+Cmb_D

which is

d20 - 15 > Cmb_D - Cmb_A

This mechanic scales well by level and accounts for class differences - which to your point there are cases where you shouldn't try! This makes sense, why would a wizard every try to grapple the tough melee opponent?

That said, I might be inclined to make a 20 always win, I'll have to think about that.

It scales well for defense, in my previous example (with the +0 and +6) if the +6 wanted to grapple the +0 they need a 9. A reasonable number for both sides.

My issue is that the range of impossible went from a difference of 20 to a difference of 6. A combat maneuver can often be a last resort, to overcome some sort of issue.

To take an example from my ROTRL game (Skinsaw Murders spoilers)

Spoiler:
To help combat Xanesha's ridiculously high AC one of my players (a 6th level Rangerm with improved trip) tried to trip her, but with her CMB of 20 (13 BAB + 6 STR + 1 size)even that was impossible. I don't mind it being hard, or even really hard, but impossible?

I can see this frustrating characters that want to focus their characters on tripping or grappling. Unless, they're a Barbarian with strength surge.

My issue with CMB as written is that between evenly matched opponents, you have a 70% failure rate (1-20 vs 15). Even a specialist vs non-specialist has a failure rate of 50%.

Pathfinder Pawns Subscriber

PRPG page 150:

"Rolling a natural 20
while attempting a combat maneuver is always a success,
while rolling a natural 1 is always a failure."

eldrwyrm wrote:
My issue with CMB as written is that between evenly matched opponents, you have a 70% failure rate (1-20 vs 15). Even a specialist vs non-specialist has a failure rate of 50%.

We treid to grapple with CMB, and maynbe we got something wrong, but with one grapller having a CMB of 5 higher than the other, the first one hass a success rate of 50%, but it doesn't matter because the other has a success rate of 0% (or 5% with a natural 20).

Purple Dragon Knight wrote:

PRPG page 150:

"Rolling a natural 20 while attempting a combat maneuver is always a success, while rolling a natural 1 is always a failure."

Thanks for clearing up the current state of Beta.

...I still feel sort of wierd about 5% of Kittens taking down Great Worms or Tarrasques (etc)

And doubly, it's kindof wierd that MELEE Critical Hits require Confirmation, but Maneuvers don't.
...Perhaps Maneuvers could be "Confirmed" by some sort of Saving Throw, either on part of Attacker or Target????

/shrug

DitheringFool wrote:
I guess I look at it in the same light as a wizard casting spells... Would Merlin cast hold person on a rival wizard? With a Will negates saving throw, I think not. He might cast it on Conan with more optimistic results...

I think someone has severely under-estimated Conan. If Merlin is decideing what spell to cast on Conan, he obviously has bigger problems, mainly that he's fighting Conan.

Anyway, adressing the real matter. I believe you have a point about it being a numbers game and having to be aware of the capabilites of your enemies.