I'm working on my cavalier's build, and I've run into some confusion with the Mounted Combat Feat.
Once per round when your mount is hit in combat, you may attempt a Ride check (as an immediate action) to negate the hit. The hit is negated if your Ride check result is greater than the opponent’s attack roll.
1) If an enemy succeeds on a CMB check against my mount, does that count as a 'hit' that I can counter with a Ride check?
2) If my mount is grappling an enemy, can I use a Ride check to counter if the enemy hits my mount on its turn?
3) If my mount is grappling an enemy, can I use a Ride check to counter their standard action attempt to take over the grapple with a CMB check?
If Mounted Combat doesn't work in any or all of those 3 circumstances, what about the Bodyguard Feat?
When an adjacent ally is attacked, you may use an attack of opportunity to attempt the aid another action to improve your ally’s AC. You may not use the aid another action to improve your ally’s attack roll with this attack.
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.
An attack roll represents your attempt to strike your opponent on your turn in a round. When you make an attack roll, you roll a d20 and add your attack bonus. (Other modifiers may also apply to this roll.) If your result equals or beats the target’s Armor Class, you hit and deal damage.
'It would seem as if combat maneuvers "hit" the target, so Mounted Combat should negate them.
1): If they succeed on a combat maneuver, yes.
3): Yes, as attempting to control the grapple is basically just making a Grapple check.
I don't think Mounted Combat would help if the enemy just tried to escape the grapple, and it definitely wouldn't help if they use Escape Artist.