Abraxas said:
The difference is the "cleaver" did it on the "cleaver's" turn not on the "cleavee's" turn.
This is such an easy concept. I just don't understand why people don't understand it?
The Cleave rule is broken (and yes, I will use the 'b' word). It should only be on your turn. Then it wouldn't be broken.
Fred opens a vial and provokes an AoO.
Killer wipes Fred out.
Killer sunders Barney's shield (Cleave and Improved Sunder)
Killer trips Barney (Combat Brute and Improved Trip)
Killer rages, attacks the prone Barney at +6 to hit and hits him (or sunders his weapon or whatever) (Instantaneous Rage)
Killer Shakens another (or the same) opponent within 30 feet (Intimidating Rage)
All because Fred opened a vial?
And what if all of this happened because Killer's spell casting ally cast Monster Summoning III and Killer has Great Cleave and did all of this 3 or 4 times outside of his turn? That's more powerful in some ways than Time Stop.
Cleave with AoO has the (very easy) potential to be STRONGER than a feat for a spell caster that allowed him to cast spells outside of his turn. Would you allow casting outside the character's turn in your game? If not, why would you allow a boatload of combat feats outside the character's turn in your game?
It is all about balance.
People generally do not have a problem with this being done on a character's turn. We just have a problem with it being done outside his turn.
If a feat gives an additional attack (for whatever reason), it should not be allowed during an AoO. Period.
The only attack you should get during an AoO is the AoO itself.