Large creatures AoO

[Brawldennis]

I'm looking for some help with the rules on attacks of opportunity, I always figured I had the rules correct, but my last DM ruled it differently and wouldn't budge on the matter. Having switched DM's in our group I figured now would be the best moment to challenge this ruling.

So let's say you're playing a character with a reach weapon and you're fighting a large creature with only 5ft. reach, a crocodile for example.

Now the crocodile charges you, moving through your reach of 10ft. to you hit. My ruling would be that he provokes an Attack of opportunity because a part of the creature leaves one of your threatened squares.

My old DM however ruled that the creature wouldn't provoke an AoO because there is still a part of the creature in the square that you threaten.

I'd love to hear you all on this.

[Darksol the Painbringer]

The rule is that if you perform movement in a square a creature threatens, you provoke, full stop.

In both instances described above, the creature would provoke.

[Bill Dunn]

To amplify Darksol's statement, a multi-square creature doesn't have to completely leave a square to provoke the AoO. Part of the creature leaving the square is sufficient, even if another part of the creature is occupying the square in question. The pertinent fact is that the creature passed through squares the character could threaten thus provoking the attack of opportunity.

[Davor]

Look at it this way: With his rule, an elephant could walk through a medium-sized creature's area, turn around, and sit down without ever provoking an attack of opportunity. It basically means that larger creatures would almost never provoke, which is nonsensical.

To be fair, his heart is in the right place. Technically, the "creature" hasn't left the square, but according to the rules it has moved to a different square, which means it had to leave a previous square. Think of a large, huge, etc. creature as being comprised of multiple 5' squares. When it leaves one, a new part of the creature moves to occupy the previous space.

But really, what it boils down to is that size does not affect the way AoOs are done.

[psychie]

Also, if I recall correctly, moving through a threatened area provokes just as much as leaving a threatened area, so even if the crocodile isn't technically "leaving" the threatened area, it is definitely and unambiguously moving through the threatened area, and thus provokes regardless of the semantics of "leaving."