AC bonuses adding to CMD... when?

[Thalin]

So in a PFS game recently, my Archivist Bard and the crew he was working with ran into some random statues that got free trip attacks when they hit.

My archivist has his Naturalist (gives a bonus to AC), and he has Bodyguard (lets him do AOOs vs attacks to add to AC).

The GM ruled that neither of these could actually add to CMD. Looking afterwards (I allowed the ruling through because I hate arguing with GMs during the game), I could not find any supporting rulings to the contrary that would say I could add them. But I remember some ruling somewhere that said if it did not say otherwise, AC bonuses work with CMD.

Any clues/insight?

[Greylurker]

CMD gets Circumstance, Deflection, Dodge, Insight, Moral , Profane and Sacred bonuses to AC (core rules Page 199, 2nd last Paragraph first column (just look for the Size adjustments, comes right after those), if you need a reference)

Naturalist should work (Insight bonus)

Bodyguard, not sure. It counts as Aid another which doesn't list a bonus type so that could be DM's call

[Bizbag]

Greylurker wrote:

CMD gets Circumstance, Deflection, Dodge, Insight, Moral , Profane and Sacred bonuses to AC (core rules Page 199, 2nd last Paragraph first column (just look for the Size adjustments, comes right after those), if you need a reference)

Naturalist should work (Insight bonus)

Bodyguard, not sure. It counts as Aid another which doesn't list a bonus type so that could be DM's call

As a GM, I'd ad hoc that it'd count as a circumstance bonus for this purpose (since that'd stack and isn't lost when flat-footed- you can still distract your opponents if your friend is helpless).

It is up to the individual GM though; I could see rulings going several ways and all having legitimacy.

[Thalin]

Unfortunately this is PFS; so I cannot ad hoc. And as a player I tend to go in favor of the most RAW ruling. So if there's not a ruling that explicitly allows me to aid another for CMD, I am not going to attempt to Deflect (use bodyguard) for CMB attacks.

I do appreciate the link on the CMD though Greylurker; I will add that to my "Buff card" that I put out on the table when I am doing my performance :).

[Cao Phen]

This is form the prd:

Combat Maneuver Defense: Each character and creature has a Combat Maneuver Defense (or CMD) that represents its ability to resist combat maneuvers. A creature's CMD is determined using the following formula:

CMD = 10 + Base attack bonus + Strength modifier + Dexterity modifier + special size modifier

The special size modifier for a creature's Combat Maneuver Defense is as follows: Fine –8, Diminutive –4, Tiny –2, Small –1, Medium +0, Large +1, Huge +2, Gargantuan +4, Colossal +8.

Some feats and abilities grant a bonus to your CMD when resisting specific maneuvers. A creature can also add any circumstance, deflection, dodge, insight, luck, morale, profane, and sacred bonuses to AC to its CMD. Any penalties to a creature's AC also apply to its CMD. A flat-footed creature does not add its Dexterity bonus to its CMD.