No: "While casting a spell, you don’t threaten any squares around you."Greybar said:* can you make an AoO while involved in a Full Round casting action?
Sure. There's nothing prohibiting this except maybe the Improved Overrun feat.Greybar said:* can you Avoid an overrun while casting, perhaps just while making a "Vigorous motion" concentration check?
There's nothing that explicitly says you should make a concentration check, so it's up to the DM. A DC 15+SL Concentration check would not be out of line, though.Greybar said:* if you're knocked prone while casting, but take no damage, should you have to make a "Violent motion" concentration check?
It should be the same, yes. I agree with that.Greybar said:* wouldn't there be a similar issue if casters were Bull Rushed or Tripped?
I don't think so.Greybar said:Maybe there's a Rules of Game article on this?
The FAQ says this about snakes:PJSlavner said:*I am not sure how a snake could be knocked prone, but if it could, violent motion seems reasonable.
Strangely, it then goes on to say that you cannot trip a snake. So, you can make a snake prone by overrunning it, but you can't make it prone by tripping it.3.5 Main FAQ said:Given that being prone means you are lying on the ground (Player’s Handbook, page 311), who can be prone? Can oozes be prone? What about creatures with no limbs like snakes? What about incorporeal creatures?
Anybody can be “prone.” Creatures that use limbs for locomotion can use a free action to drop prone and must use a move action to stand up again. Something with no motive limbs, such as a snake, can go prone or “stand up” as a free action. Such creatures might want to become prone to gain an Armor Class bonus against ranged attacks. (Although giving something like a gelatinous cube that option defies common sense and should not be allowed.) Officially, there’s an attack of opportunity any time a creature stands up. The Sage, however, heartily recommends no attack of opportunity when a snake or similar creature “stands up.”