Variant Combat Maneuver Checks (3.5e Variant Rule)

Variant Combat Maneuver Checks
One of the interesting things Pathfinder did was compressing various combat maneuvers, such as disarm, grapple, and trip, into a single event of Combat Maneuver Bonus vs Combat Maneuver Defense. It was actually quite smart. No longer did one have to remember if the disarm was an opposed ability roll, or opposed attack rolls, or the 1000 steps of grappling. It was simple and clear, as good as attack vs AC. And it meant one could expand any unusual stunt or dirty trick into a CMB vs CMD. It made sense.

However, it was also considered a stealth nerf, for while CMB is based on 1d20 + BAB + Str, CMD is 10 + BAB + Str + Dex, meaning when one has a strong Str and Dex, one was all but invulnerable. This isn't a problem against other PCs, but you know who often has good Str and Dex, and ability scores above and beyond what players can have to make up for the lack of magical gear and class levels? Monsters. And so, combat maneuvers are very difficult to pull off.

Thus this rule is functional in both 3.5 and Pathfinder. 3.5 gain the benefits of the CMB vs CMD concept, and Pathfinder gets to fix theirs to place the balance away from the monsters it favors. This is variant combat maneuver checks.

Combat Maneuver Bonus
The combat maneuver bonus retains one bit of granularity from 3.5 that is important. Rather than 1d20 + BAB + Str, the bonus is now 1d20 + BAB + appropriate ability modifier as shown below.

Bull Rush: Strength.

Disarm: As used for attack rolls (usually either Strength or Dexterity).

Grapple: Strength.

Overrun: Strength.

Sunder: Strength.

Trip: Strength.

Others: As appropriate, either strength or dexterity. For example, throwing dirt in someone's eye is likely dexterity.

Combat Maneuver Defense
The combat maneuver defense is split in two, into combat strength defense and combat dexterity defense (10 + BAB + Str and 10 + BAB + Dex respectively). Use whichever is higher to oppose the combat maneuver bonus.

Certain abilities may allow a creature to specifically target your weaker bonus. The big important part is that it only has one, not two, ability modifiers stacking and makes the defense much more reasonable.