Attack Bonus = CMB?

[Dr Sarcasm]

Been reading up on CMB for a dispelling weapon in regards to spell sunder.

Quote:

When you attempt to perform a combat maneuver, make an attack roll and add your CMB in place of your normal attack bonus. Add any bonuses you currently have on attack rolls due to spells, feats, and other effects. These bonuses must be applicable to the weapon or attack used to perform the maneuver.

Ok, so what's an attack roll as defined by the Core Rulebook?

Quote:

Your attack bonus with a melee weapon is:

Base attack bonus + Strength modifier + size modifier

And CMB?

Quote:

CMB = Base attack bonus + Strength modifier + special size modifier

So my CMB is exactly equal to my normal attack roll. And as mentioned above, it is affected by any bonuses and penalties my normal attack roll is. Which means that when performing a spell sunder with a +2 dispelling weapon, I am making a standard attack action vs the opposing CMD.

Am I getting this right? That my CMB is effectively my regular attack roll when using a weapon-based combat maneuver?

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And while I'm here, a dispelling weapon's description reads

Quote:

A dispelling weapon functions like a spell storing weapon, but it may only store dispel magic; however, the caster level check to dispel gains an additional bonus equal to the weapon's enhancement bonus. This bonus also applies to a magus's dispelling strike arcana or a barbarian's spell sunder or sunder enchantment combat maneuver check.

Is this bonus an untyped bonus, or an enhancement bonus? I'd say the former, otherwise the two enhancement bonuses would cancel out the other.

[CampinCarl9127]

For 95% of PCs, the bonuses to melee attacks and CMB is the same. But there are abilities that can alter one without altering the other (weapon focus, improved trip, etc.) They are very often the same, but not always.

It's an untyped bonus and thus stacks.

[Snowblind]

It isn't the same for characters that aren't medium. A small character takes a size penalty to CMB, but gets a bonus to attack.

Also, some CMB rolls don't apply weapon bonuses (escaping a grapple, for example).

[Fromper]

Note that the size bonus for regular attacks is not the same as the special size bonus in CMB. For regular attacks, being smaller helps your chance to hit. For CMB, being smaller is a penalty, and being larger helps.

[Jiggy]

One important thing to note is that CMB uses a different size modifier than your normal attacks (that's why the quoted formula says "special" size modifier).

Otherwise, yes, your CMB for a weapon-based maneuver (which not all maneuvers are) will often be the same as your typical attack bonus, plus any maneuver-specific bonuses (i.e., "Improved [Maneuver]" feats).

EDIT: Double ninja'd.

[Dr Sarcasm]

Sweet, thanks.