Grappling an "overrunning" character

[Hussar]

But, you can take free actions, even when its not your turn. Speaking is a free action that may be taken at any time.

The reason you can't use a quickened spell has nothing to do with its action type, but, rather, the fact that an AOO MUST be a melee attack. For exactly the same reason that a character with reach, spiked armor and a bow couldn't make his AOO with his bow. He has to use the threatening weapon.

That needs to be reiterated - you can only take an AOO with the attack that threatens - your primary melee attack. You cannot use another weapon, nor could a creature with a bite/claw/claw (presuming bite is primary) use a claw for an AOO, even if the claw was a superior choice (through improved grab for instance).

You can make any normal melee attack with an AOO. Sunder, grapple, trip, etc, are all normal melee attacks. Thus, in the OP's case, the trampler gets grappled, his movement stops at that point and deals no damage because of the grapple.

 

[Hypersmurf]

But, you can take free actions, even when its not your turn. Speaking is a free action that may be taken at any time.

Speaking is a free action with a special note that it "can be performed even when it isn't your turn".

It's an exception, like Feather Fall in the published PHB.

That needs to be reiterated - you can only take an AOO with the attack that threatens - your primary melee attack. You cannot use another weapon, nor could a creature with a bite/claw/claw (presuming bite is primary) use a claw for an AOO, even if the claw was a superior choice (through improved grab for instance).

A creature with bite/claw/claw threatens with all three weapons, and could elect to make his AoO with any of them. The -5 attack penalty for a secondary weapon and half Str bonus to damage would apply if he chose to use a claw, but he certainly has the option.

-Hyp.

 

[KarinsDad]

But, you can take free actions, even when its not your turn. Speaking is a free action that may be taken at any time.

Not only is Speaking a special case free action, but it is also optional. A DM does not have to allow Speaking outside a character's turn (as per the PHB, not the SRD).

 

[RigaMortus2]

But, you can take free actions, even when its not your turn. Speaking is a free action that may be taken at any time.

The reason you can't use a quickened spell has nothing to do with its action type, but, rather, the fact that an AOO MUST be a melee attack.

If we are assuming you CAN perform free actions when it is not your turn, you could cast (for example) a Quickened Inflict X Wounds spell. It is a free action to perform, which gives you a melee (touch) attack. You can then use this melee (touch) attack as your AoO.

 

[Hussar]

If we are assuming you CAN perform free actions when it is not your turn, you could cast (for example) a Quickened Inflict X Wounds spell. It is a free action to perform, which gives you a melee (touch) attack. You can then use this melee (touch) attack as your AoO.

Hang on, Quicken Spell is a Swift action, not a free action:

Quicken Spell [Metamagic]
Benefit

Casting a quickened spell is an swift action. You can perform another action, even casting another spell, in the same round as you cast a quickened spell. You may cast only one quickened spell per round. A spell whose casting time is more than 1 full round action cannot be quickened. A quickened spell uses up a spell slot four levels higher than the spell’s actual level. Casting a quickened spell doesn’t provoke an attack of opportunity.

Solves that problem doesn't it?

And, as far as using secondary attacks for AOO's, the SRD does say this:

Attack
This line shows the single attack the creature makes with an attack action. In most cases, this is also the attack the creature uses when making an attack of opportunity as well.

True, it does say in most cases, so, it is possible for a creature to use a secondary attack, but, unless there's a very specific reason why not, I would interpret that to mean that it uses its primary attack for AOO's.