Rise of the Runelords

Possibly the change with the greatest impact is the implementation of the Combat Maneuver roll. The below is from the Pathfinder Rules.

During combat, you can attempt to perform a number of maneuvers that can hinder or even cripple your foe, including bull rush, disarm, grapple, overrun, sunder, and trip. Although these maneuvers have vastly different results, they all use a similar mechanic to determine success.

Combat Maneuver Bonus
Each character and creature has a Combat Maneuver Bonus (or CMB) that represents its skill at performing combat maneuvers. A creature's CMB is determined using the following formula:

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

Creatures that are size Tiny or smaller use their Dexterity modifier in place of their Strength modifier to determine their CMB. The special size modifier for a creature's Combat Maneuver Bonus 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 CMB when performing specific maneuvers.

Performing a Combat Maneuver: When performing a combat maneuver, you must use an action appropriate to the maneuver you are attempting to perform. While many combat maneuvers can be performed as part of an attack action, full-attack action, or attack of opportunity (in place of a melee attack), others require a specific action. Unless otherwise noted, performing a combat maneuver provokes an attack of opportunity from the target of the maneuver. If you are hit by the target, you take the damage normally and apply that amount as a penalty to the attack roll to perform the maneuver. If your target is immobilized, unconscious, or otherwise incapacitated, your maneuver automatically succeeds (treat as if you rolled a natural 20 on the attack roll). If your target is stunned, you receive a +4 bonus on your attack roll to perform a combat maneuver against it.

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. The DC of this maneuver is your target's Combat Maneuver Defense. Combat maneuvers are attack rolls, so you must roll for concealment and take any other penalties that would normally apply to an attack roll.

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, 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.

Determine Success: If your attack roll equals or exceeds the CMD of the target, your maneuver is a success and has the listed effect. Some maneuvers, such as bull rush, have varying levels of success depending on how much your attack roll exceeds the target's CMD. Rolling a natural 20 while attempting a combat maneuver is always a success (except when attempting to escape from bonds), while rolling a natural 1 is always a failure.

Bull Rush
You can make a bull rush as a standard action or as part of a charge. You can only bull rush an opponent who is one size category larger than you or smaller. A bull rush attempts to push an opponent straight back without doing any harm. If you do not have the Improved Bull Rush feat, or a similar ability, initiating a bull rush provokes an attack of opportunity from the target of your maneuver. If your attack is successful, your target is pushed back 5 feet. For every 5 by which your attack exceeds the DC you can push the target back an additional 5 feet. You can move with the target if you wish but you must have the available movement to do so. If your attack fails, your movement ends in front of the target.

Disarm
You can attempt to disarm your opponent as part of an attack action in place of a melee attack. If you do not have the Improved Disarm feat, or a similar ability, attempting to disarm a foe provokes an attack of opportunity from the target of your maneuver. Attempting to disarm a foe while unarmed imposes a –4 penalty on the attack. If your attack is successful, your target drops one item it is carrying (of your choice). If your attack exceeds the DC of the target by 10 or more, the target drops the items it is carrying in both hands (maximum two items if the target has more than two hands). If your attack fails by 10 or more, you drop the weapon that you were using to attempt the disarm. If you successfully disarm your opponent without using a weapon, you automatically pick up the item dropped.

Grapple
As a standard action, you can attempt to grapple a foe, hindering his combat options. If you do not have Improved Grapple, improved grab, or a similar ability, attempting to grapple a foe provokes an attack of opportunity from the target of your maneuver. Humanoid creatures without two free hands attempting to grapple a foe take a –4 penalty on the combat maneuver roll. If successful, both you and the target gain the grappled condition (see the Glossary chapter). If you successfully grapple a creature that is not adjacent to you, move that creature to an adjacent open space (if no space is available, your grapple fails). If you successfully grapple an opponent, you must continue to make a check each round, as a standard action, to maintain the hold. If your target does not break the grapple, you get a +5 circumstance bonus on grapple checks made against the same target in subsequent rounds. Once you are grappling an opponent, a successful check allows you to continue grappling the foe, and also allows you to perform one of the following actions.

Move: You can move both you and your target up to half your speed. At the end of your movement, you can place your target in any square adjacent to you. If you attempt to place your foe in a hazardous location, such as in a wall of fire or over a pit, the target receives a free attempt to break your grapple with a +4 bonus.

Damage: You can inflict damage to your target equal to your unarmed damage. This damage can be either lethal or nonlethal.

Pin: You can give your opponent the pinned condition. Despite pinning your opponent, you still only have the grappled condition, but you lose your Dexterity bonus to AC.

If you are grappled, you can attempt to break the grapple as a standard action by making a combat maneuver check (DC 15 + opponent’s CMB, this does not provoke an attack of opportunity) or Escape Artist check (DC 10 + opponent’s CMB). If you succeed, you break the grapple and can act normally.

If you have your target pinned or otherwise restrained, or unconscious, you can use rope to tie them up. This works like a pin effect, but with a + 5 circumstance bonus to determine the DC to escape the bonds (making the DC equal to 20 + your CMB). The ropes do not need to make a check every round to maintain the pin. If you are grappling the target, you can attempt to tie him up in ropes, but doing so requires a combat maneuver check at a –10 penalty.

Overrun
As a standard action taken during your move, or as part of a charge, you can attempt to overrun your target, moving through its square. You can only overrun an opponent who is one size category larger than you or smaller. If you do not have the Improved Overrun feat, or a similar ability, initiating an overrun provokes an attack of opportunity from the target of your maneuver.

When you attempt to overrun a target, it can choose to avoid you, allowing you to pass through its square without requiring an attack. If your target does not avoid you, make a combat maneuver attack roll as normal. If your attack is successful, you move through the target’s space. If your attack exceeds the DC by 5 or more, you move through the target’s space and the target is knocked prone. If the target has more than two legs, add +2 to the DC of the combat maneuver attack roll for each additional leg it has.

Sunder
You can attempt to sunder an item held or worn by your opponent as part of an attack action in place of a melee attack. If you do not have the Improved Sunder feat, or a similar ability, attempting to sunder an item provokes an attack of opportunity from the target of your maneuver.

You must be wielding a weapon to attempt a sunder. If your attack is successful, you deal damage to the item normally. If the damage you deal exceeds the object’s hardness, the object gains the broken condition (see the Glossary chapter). If the damage you deal exceeds the object’s hardness and hit points, you can choose to destroy it. If you do not choose to destroy it, the object is left with only 1 hit point.

Trip
You can attempt to trip an opponent as a melee attack. You can only trip an opponent who is one size category larger than you or smaller. If you do not have the Improved Trip feat, or a similar ability, initiating a trip provokes an attack of opportunity from the target of your maneuver.

If your attack is successful, the target is knocked prone. If your attack fails by 10 or more, you are knocked prone instead. If the target has more than two legs, add +2 to the DC of the combat maneuver attack roll for each additional leg it has. Some creatures, such as oozes without legs and f lying creatures, cannot be tripped.

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