Can you Overrun flying foes?

[JLendon]

Hello, is there anything wrong with using Greater Overrun while flying to tackle through a flying character, knocking it prone if CMB is 5 or more than CMD (or at least making it lose altitude and forcing it to make a fly check to stay aloft if it uses wings)? I think, with the successful Overrun CMB of 5 or more vs CMD, the PC would get the AOO from Greater Overrun, plus an AOO kick as it drops altitude with the Vicious Stomp feat. If the overrun creature uses Air Walk for it's flight, then it might even literally be knocked prone in the air and have to stand up from prone to move anywhere.

Keep in mind that being "knocked prone" is different than being "tripped", and trip immunity from flight doesn't apply.

What do you think?

[JLendon]

No one is answering. Do you consider this a silly question?

[Shadowborn]

The PRD wrote:

Prone: The character is lying on the ground.

Emphasis mine.

You can't be prone while flying.

[SwiftyKun]

TL;DR To answer your question, yes, a flying target can be overrun and knocked prone. See below for details.

Overrun:

Overrun

As a standard action, taken during your move or as part of a charge, you can attempt to overrun your target, moving through its square. You can only overrun an opponent who is no more than one size category larger than you. If you do not have the Improved Overrun feat, or a similar ability, initiating an overrun provokes an attack of opportunity from the target of your maneuver. If your overrun attempt fails, you stop in the space directly in front of the opponent, or the nearest open space in front of the creature if there are other creatures occupying that space.

When you attempt to overrun a target, it can choose to avoid you, allowing you to pass through its square without requiring an attack. If your target does not avoid you, make a combat maneuver check as normal. If your maneuver is successful, you move through the target's space. If your attack exceeds your opponent's CMD by 5 or more, you move through the target's space and the target is knocked prone. If the target has more than two legs, add +2 to the DC of the combat maneuver attack roll for each additional leg it has.

Fly Movement:

Fly
(Dex; Armor Check Penalty)

You are skilled at flying, through either the use of wings or magic, and can perform daring or complex maneuvers while airborne. Note that this skill does not give you the ability to fly.

Check: You generally need only make a Fly check when you are attempting a complex maneuver. Without making a check, a flying creature can remain flying at the end of its turn so long as it moves a distance greater than half its speed. It can also turn up to 45 degrees by sacrificing 5 feet of movement, can rise at half speed at an angle of 45 degrees, and can descend at any angle at normal speed. Note that these restrictions only apply to movement taken during your current turn. At the beginning of the next turn, you can move in a different direction than you did the previous turn without making a check. Taking any action that violates these rules requires a Fly check. The difficulty of these maneuvers varies depending upon the maneuver you are attempting, as noted on the following chart.
Flying Maneuver Fly DC
Move less than half speed and remain flying 10
Hover 15
Turn greater than 45° by spending 5 feet of movement 15
Turn 180° by spending 10 feet of movement 20
Fly up at greater than 45° angle 20

Attacked While Flying: You are not considered flat-footed while flying. If you are flying using wings and you take damage while flying, you must make a DC 10 Fly check to avoid losing 10 feet of altitude. This descent does not provoke an attack of opportunity and does not count against a creature's movement.

Collision While Flying: If you are using wings to fly and you collide with an object equal to your size or larger, you must immediately make a DC 25 Fly check to avoid plummeting to the ground, taking the appropriate falling damage.

Avoid Falling Damage: If you are falling and have the ability to fly, you can make a DC 10 Fly check to negate the damage. You cannot make this check if you are falling due to a failed Fly check or a collision.

High Wind Speeds: Flying in high winds adds penalties on your Fly checks as noted on Table: Wind Effects on Flight. “Checked” means that creatures of that size or smaller must succeed on a DC 20 Fly check to move at all so long as the wind persists. “Blown away” means that creatures of that size or smaller must make a DC 25 Fly check or be blown back 2d6 × 10 feet and take 2d6 points of nonlethal damage. This check must be made every round the creature remains airborne. A creature that is blown away must still make a DC 20 Fly check to move due to also being checked.
Table: Wind Effects on Flight Wind Force Wind Speed Checked Size Blown Away Size Fly Penalty
Light 0–10 mph — — —
Moderate 11–20 mph — — —
Strong 21–30 mph Tiny — –2
Severe 31–50 mph Small Tiny –4
Windstorm 51–74 mph Medium Small –8
Hurricane 75–174 mph Large Medium –12
Tornado 175+ mph Huge Large –16

Action: None. A Fly check doesn't require an action; it is made as part of another action or as a reaction to a situation.

Try Again: Varies. You can attempt a Fly check to perform the same maneuver on subsequent rounds. If you are using wings and you fail a Fly check by 5 or more, you plummet to the ground, taking the appropriate falling damage (see Environment).

Special: A spellcaster with a bat familiar gains a +3 bonus on Fly checks.

Creatures with a fly speed treat the Fly skill as a class skill. A creature with a natural fly speed receives a bonus (or penalty) on Fly skill checks depending on its maneuverability: Clumsy –8, Poor –4, Average +0, Good +4, Perfect +8. Creatures without a listed maneuverability rating are assumed to have average maneuverability.

A creature larger or smaller than Medium takes a size bonus or penalty on Fly checks depending on its size category: Fine +8, Diminutive +6, Tiny +4, Small +2, Large –2, Huge –4, Gargantuan –6, Colossal –8.

You cannot take ranks in this skill without a natural means of flight or gliding. Creatures can also take ranks in Fly if they possess a reliable means of flying every day (either through a spell or other special ability).

If you have the Acrobatic feat, you get a bonus on Fly checks (see Feats).

I don't care going through all of the text to quote every bit of information, but basically if the flying target chooses to not get out of the way of the overrun attempt(which they can do as a free action and will 99.99% of the time), then the collision rules for flying movement come into play. If they are in a collision sparked from you hitting it or it hitting something else, it falls. If it falls and takes lethal damage, it's knocked prone. If it takes non-lethal damage, it is now standing on the ground. If it is on the ground, normal overrun rules apply when used against it. As for the improved and greater variants, the target may not choose to avoid you, thus you skip that step and continue with the collision rules as normal. If they fail the fly check you get a free AoO when they hit the ground and take their falling damage(if lethal).

[JLendon]

Thanks for your replies. I did mention that the PC was using Greater Overrun, which implies Improved, and therefore there's no choice to avoid the overrun. Since the rules for AOO's say the AOO from knocking a creature prone occurs BEFORE they actually receive the prone condition, the PC should get the AOO (with no prone bonus) as the creature is on it's way down, realistically a kick within the first 5' of falling, and it wouldn't matter if the victim makes it's fly check, a few seconds later, as it's falling, to avoid hitting the ground and becoming prone.

Overrun says that they ARE knocked prone if the overrun is 5 or more than the CMD of the creature, and Greater Overrun gives you the AOO as they are following through with act of being knocked prone (falling down). Even if the creature has MAGICAL flight, a 5+ Overrun should have the effect of causing the creature to maybe lose it's balance, spinning vertically once or twice before regaining control, which allows the AOO from Greater Overrun and Vicious Stomp.

This does raise another question, does the act of overrunning cause the PC to have to make a collision check as well as the target? Is committing an overrun (or bull rush or trample?) counted as a collision for both parties? The initiator is in control of the maneuver, hoping to overcome the target. Although, the rules for flying say if you are ATTACKED you can lose 10' if you fail a fly check. A combat maneuver is an attack, not a collision. But really, a flying grapple, overrun, bull rush, etc. is more of a collision.

Also, Air Walk says, "The subject can tread on air as if walking on solid ground. Moving upward is similar to walking up a hill." That is why I think I could literally use a flying overrun to knock a character using air walk prone so that it has to stand up from prone on it's turn.

[Cleanthes]

Note that the RAW say you have to make a Fly check to avoid falling after a collision if you're using wings to fly. Most flying PCs (obviously not all) are going to be flying with a fly spell or the like, and so won't have to worry about that check. I'm playing an air elementalist right now, and once he hits level 10 and can fly at will, I've been considering using just this tactic on other flying creatures to try to make them fall, or maybe using Bigby's hand spells (I know they're not Bigby's anymore, so sue me) to achieve the same effect.

[Lord_Malkov]

Few things.

[1] You can't knock a flying creature prone. To be prone, one must be lying on the ground. A flying creature does not meet the conditions necessary.
Any creature immune to trip will not be knocked prone by an Overrun. Immune to trip = cannot be prone. Or rather: Tripped = Knocked Prone, so Cannot be Tripped = Cannot be Knocked Prone.
A gelatinous cube can't be knocked prone because it is an omnidirectional cube. This doesn't change based on which maneuver or spell you are using. Tripped in this sense is not referring to the maneuver.

Flying creatures also cannot be knocked prone (so long as they are flying, you can indeed cause them to plummet).

[2] A collision while flying requires the creature to collide with an [b]object[/i] not another creature. Otherwise every natural attack made against a flying creature would cause them to drop like rocks. This can come up, a creature with Rock Throwing for example, can throw rocks up to two size categories smaller than itself. So it could knock a flying creature out of the air if it was two size categories smaller than itself. You can also achieve this effect with certain walls and conjuration spells.

[3] Yes, of course you can overrun a target that is flying, you just can't knock them prone while doing so. This would require them to make a fly check because they have been attacked. In the case of Air Walk, they are NOT flying and therefore are not immune to being knocked prone, so yes, they are fair game.

[Lord_Malkov]

As a side note, the Collision rules are a great way to down a Dragon that might be harrassing your group with Flyby Attacks.

Just ready an action to summon a wall right in its face when it is swooping in for its next attack. Instant bug-on-a-windshield. Dragons tend to have pretty poor fly skills.

[JLendon]

Lord Malkov, I admit that you've persuaded me about not being able to knock a flying creature prone, but not because they are immune to being tripped, but only because they aren't being made prone by my attack...especially if they have magical flight. If they use wings, I think there is still some gray area.

The rules actually say that flying creatures and those without legs are immune to being TRIPPED, which is one way to be knocked prone. If you are tackled and knocked off your feet and pushed onto your butt, were you tripped? There is a whole discussion of this on at the link below. Granted, there was no resolution in that discussion, but being tripped and being knocked prone by overrun are two different methods of ending up prone. Some are immune to the former. But this may be splitting hairs, I agree. I suppose they should just say that certain creatures cannot be made prone, period.

The official FAQ answer for Greater Trip and Vicious Stomp says, "Yes, the two triggering acts are similar here but they are different. One occurs when you trip a foe. The other occurs when a foe falls prone." This DOES seem to make the distinction of using "Tripped" as a maneuver and any different method of knocking something prone.

The aforementioned link:
http://paizo.com/threads/rzs2p5wn?Can-a-snake-be-knocked-prone