In the context of Pathfinder Society:
1. If, when using acrobatics to avoid attacks of opportunity, a character moves through a square threatened by multiple foes, is the acrobatics check to avoid AoOs:
(a) Made once (with the DC increased appropriately for the correct # of foes), with the single result applied to all foes;
or
(b) Made separately for each foe, with the DC increasing by 2 for each subsequent foe beyond the first?
After multiple readings of Acrobatics, I can see why it could be interpreted either way.
2. If one fails the Acrobatics check to move through an opponents space, does movement immediately end? Does the character failing the check fall prone?
1. Because the acrobatics check is versus the opponents' CMD (rather than a static DC as in 3.5) it pretty much has to be (b), since different opponents will most often have different CMDs to overcome.
As a DM I always run it as the extra +2 to subsequent acrobatics checks. By this I mean if the character moves through the threatened area of more than 1 creature, I go in order of when the character provokes. So say a character is moving from square A through squares B and C and into square D and is using the acrobatics skill to avoid AoOs. By moving out of A he provokes from monster 1, at the base DC of 1's CMD. Moving out of B provokes from monster 2, at the 2's CMD +2. And moving out of C provokes from 3 and 4, and here I would give the player the option of who gets the higher DC increase (in game, the character can be giving more attention to one than the other); one of these two would have a DC of CMD +4 and the other of CMD +6.
2. I see no reason why movement would end. I think it worked that way in 3.5, but the rules don't say that in PF. A failed check simply means the character cannot enter the opponents space, and provokes an AoO for the attempt. If a character attempted and failed to move through an opponents space, I would charge the character's movement as if he had moved into the opponents space for the attempt (in most cases this would be 2 squares of movement since generally moving while using acrobatics to avoid AoOs requires moving at half speed)...of course allowing the AoO from the opponent before allowing the character to continue moving. However, if the character still had movement left I would let them finish their movement. In any event, they must end their movement in a legal space, whether they succeeded on the acrobatics check or not.
No, they don't fall prone, barring some odd circumstance (such as failing the acrobatics check to move through an opponents square but then having no legal square to return to....not sure how this might come up but if it did I would have them fall prone in the opponents square.)
Of course, failing the acrobatics check would provoke an AoO, and depending on the attack the result might be that the character is prone, such as from a trip attack...or being dropped below 0 hitpoints!
|
1. Because the acrobatics check is versus the opponents' CMD (rather than a static DC as in 3.5) it pretty much has to be (b), since different opponents will most often have different CMDs to overcome.
I contend this logic. There is no reason you could not compare one roll to several different CMDs (even CMDs modified by being additional opponents).
Beyond the mechanics question, I feel rolling fewer dice helps mitigate the situation faster, thus I choose (a). (I concede that either interpretation is valid and gladly accept either when I'm not the GM.)
|
You make a roll against each CMD, with each additional adding +2. Tom if you have to Tumble through a room filled with enemies you don't actually provoke against the last guy in the room until you pass through his threatening squares. If you blow the roll against foe #1, why should foe #4 get an AoO when you reach him?
Now if you fail your Acrobatics check to tumble THROUGH an enemies space (not merely their threatened squares) your movement for the round ends and you provoke. According to RAW if you end in an illegal square you must move back to the last legal square you occupied or the closest legal position available. I however don't believe a tumbler should be rewarded with the last clause of that rule and must go back to the last legal space they occupied.
--Vrocktoberfest
|
|
If you blow the roll against foe #1, why should foe #4 get an AoO when you reach him?
I should be more specific.
Either interpretation is valid for each instance of Acrobatics.
Under my preferred method: If you're trying to move X consecutive squares using Acrobatics to avoid AoOs, make one check. Should the check fail vs. the first CMD you compare it to, you're free to end your movement and not risk further AoOs, or resume normal movement provoking AoOs normally (but not suffering reduced movement). The same applies should you fail vs. the second or any subsequent CMD.
At some point you switch back to normal movement, after which in order to avoid AoOs for movement you would have to make another Acrobatics check.
|
|
See I'm pretty sure you can't do what you're saying either. Tumbling is an on/off choice. If you tumble in a round you move half speed the entire round unless you add +10 to the DC.
So according to your method if you blow the check vs the first CMD you don't have the option to continue moving normally. You must continue along at half speed the rest of your turn.
--Vrocking the suburbs
|
|
| 1 person marked this as FAQ candidate. |
If you tumble in a round you move half speed the entire round unless you add +10 to the DC.
There is (as far as I can see) nothing to support this conclusion. This check is made as part of movement. At most, the amount of time spent tumbling is limited to the action being used to move, but even that makes little sense.
Since the penalty to movement for using Acrobatics is imposed by the player – and nothing prevents the player from *not* tumbling – the player should be able to stop using Acrobatics at any time.
If the character only needs to move through one threatened square, why should the entire movement the character takes in the round be hampered?
2. If one fails the Acrobatics check to move through an opponents space, does movement immediately end? Does the character failing the check fall prone?
[/b]
I would personally use the old 3.5 rules where you stop but as it isn't explicitly listed as such in PFRPG (my guess would be copy&paste/page count as they merged and altered the skills and had to leave things out) we have to go through and recreate what happens in the new rule set.
Base Rules: You cannot move through a square occupied by an opponent unless that creature is helpless (PFRPG pg. 193), obstacles that don't completely block movement cost 2 squares of movement (PFRPG pg. 193), tumbling during movement is halved (PFRPG pg. 88), the only movement which doesn't provoke AoO's is the 5' step (PFRPG pg. 180), moving out of multiple squares threatened by the same opponent do not count as multiple opportunities (PFRPG pg. 180).
Exception to the Rule: Trained characters can attempt to move through a square occupied by an opponent - refer to acrobatics skill. (PFRPG pg. 193), creatures that completely fill a square cannot be bypassed even using Acrobatics (PFRPG pg. 193).
Rules for the Exception: DC to move through an occupied square is 5 + opposing CMD.
This is really all we have to work with unfortunately.
So with that we look at the situation.
A few assumptions, both creature and character are only occupying 1 square each, the character has a 30' speed and is no more than lightly encumbered (otherwise they couldn't tumble), they are on "normal" terrain (no extra movement cost), have nothing else within 1 square of each other and they are not taking the +10 to not halve movement speed. Also, neither are incoporeal, ethereal, or any fun stuff like that.
Start with the opponent and the character are next to each other (kinda important actually) and the medium character wants to tumble through the opponent. This requires the character to be tumbling and so now only has 15' of movement available. The character rolls the die and makes the attempt...
Attempt succeeds: The character now has to use 2 squares of movement to get into the opponents square which wouldn't have been possible normally. But as the character was able to succeed on the acrobatics check this becomes possible. The opponent definitely qualifies as an obstacle as per the rules listed. The character now has only 1 square of movement left and so can pass through to the other side. Remember when I said they were next to each other and it was important? If the character started anywhere else except next to the opponent they would not have had the movement available to complete the move through the opponent. This means creatures with less than 30' movement are unable to pass through opponents with Acrobatics unless they use 2 movements... Also if there is difficult terrain even a medium creature with 30' is unable to make it in one movement as it would cost at least 4 squares.
Attempt fails: This is actually where it gets tricky I guess as there are two ways to look at it. Character makes the attempt but as you not part of the exception (didn't make the acrobatics roll to become exempt) you are unable to move through the opponents square.
So I guess the non-cheesy way goes like this:
(1) In order to make the attempt you have to be using Acrobatics, as you are using acrobatics you are stuck with a halved movement action. (Otherwise you couldn't have even tried)
(2) You made the attempt to move through an opponent (which cost 2 squares of your halved movement) and when you failed the roll the rules caught up with you.
(3) You are currently sitting in the same square as the opponent -which cannot happen- so the rules gracefully dump you back to where you started from with a whopping 1 square of movement left, as for this attempt you are unable to pass through the opponent AND the opponent gets to take a swing at you if it can.
(4) Because of the way PFRPG changed the movement and AoO interaction you can take and move that 1 square without having to worry about another AoO from that opponent even though technically it is the 10'->15' part of your movement action.
You failed the roll but even though you failed because you have 1 point in the skill of acrobatics you still move through the opponent's square. All because of a really stupid * by the Base Acrobatics DC that states specifically that "This DC is used to avoid an attack of opportunity due to movement. This DC increases by 2 for each additional opponent avoided in 1 round." If it had been next to the first entry there I would have a really really really hard time justifying it. But as it actually says the DC is for the AoO it could be read that even though you fail the skill roll you can still move through the opponent after sucking up the AoO as you have Acrobatics and are tumbling through. Having the acrobatics skill makes you the exception. The table states specifically the DC is for the AoO, the exception states you can make the movement if you have the skill. This is the type of stuff that makes me wish they had left the acrobatics skill alone...
*sad panda*
I really don't think the cheesy way is intented as no one would ever NOT take a rank of acrobatics ever. Just trying to be complete.
There is (as far as I can see) nothing to support this conclusion. This check is made as part of movement. At most, the amount of time spent tumbling is limited to the action being used to move, but even that makes little sense.
Since the penalty to movement for using Acrobatics is imposed by the player – and nothing prevents the player from *not* tumbling – the player should be able to stop using Acrobatics at any time.
If the character only needs to move through one threatened square, why should the entire movement the character takes in the round be hampered?
After staring at this stuff for awhile... I have to say you both have parts of it.
Acrobatics is part of a movement (again medium critter 30' base speed) SO we have what kind of acrobatic movements available?
1) 5' step - this can't be halved nor does it provoke an AoO so we'll ignore it for this discussion
2) A movement action - this is normally what we'd be talking about for acrobatics. Our subject would decide to "tumble" and so would be able to move up to 15' for this action. This one action would be covered by a single Acrobatic check and that roll would be used against all possible opponents during that movement (with the appropriate +2 being added every time the roll was checked against)
3) 2 seperate movement actions - This would actually require 2 seperate checks, once for the first 15' movement action and another for the second 15' movement action. If there were multiple opponents the DC bumps from the first movement would be carried over to the second, the DC note says it increases for every opponent avoided in that round, not per check. So if there were 3 opponents checked against during the first movement, the first opponent checked against with the second roll associated with the second movement action would get the +6 added to the DC. And so on until the end of the 2nd movement action - 30' total movement.
Maybe you don't want to take a chance with the second roll or maybe you need to move further than the 30?
4) Run action - full round movement action that allows you to move at 4x (or 5x with the Run feat) your movement action and 1 roll as it is a single action. You cannot do this if you are on difficult terrain or if you cannot see where you are going. This means you can actually run while tumbling and get a total of 60' (75' with the feat) of movement. The down side is you lose your Dex to AC (unless you have the feat) when the opponents get to attempt AoO's on you and it has to be a straight line (unless you have a feat/ability that makes an exception to that rule).
|
In the context of Pathfinder Society:
2. If one fails the Acrobatics check to move through an opponents space, does movement immediately end? Does the character failing the check fall prone?
In the context of PFS, the answer to this is unclear and you should not be surprised to see variations. Such table variance is a normal in organized play.
Edit: My reply on the topic is here.
hi there,
Question; attempting to move through a hostile occupied square from an adjascent square, as discussed above requires an acrobatics check to succeed(established) but wouldnt a second acrobatics roll be needed to avoid AoO from leaving a threatened square?(the start point), and if the attempt fails(for passing through occupied square)and you remain where you started,-provoking an AoO for the failed attempt, the second roll would not occur(because you technically didnt leave the starting square, then attempted to move the remaining 5' of your movement (re; skylancer4's point #4 above,)you would indeed draw an attack of op, as the first AoO was for the failed move through, NOT for leaving the threatened square, which are different actions drawing AoO??
so
1)If successful on moving through occupied square with first acrobatics check still requires second acrobatics check to avoid AoO for leaving threatened square
2)after failed acrobatics check to move through will still draw AoO if use remaining movement to leave threatened square
|
|
This is the way I see it. Your DC is based on moving through a Threatened Square, so for each Threatened square you move through you need to make a roll. So if you move through 3 threatened squares that round using Acrobatics, you need to make 3 rolls. I think this is totally different then 3.5 where you only needed to make 1 roll. Since it is based on a Square and the DC goes up per each additional opponent avoided you only roll once per square based on the highest CMD of the multiple opponents.
In addition, you can move through a threatened square without provoking an attack of opportunity from an enemy by using Acrobatics.
As an example you are in front of one opponent (1) there is one directly behind that opponent (2) and another directly behind that one (3) that you want to get behind. You go diagonally left which does not provoke since it is the first 5' then go 1 Forward which is when you need to start your acrobatics with provoking 2 AoOs, opponent 1 has a CMD of 14, opponent CMD of 16 so for that square you target is 16+2 which is 18 you roll a 18 so you are good!. You continue your acrobatics continuing straight so you are just left of opponent 3 which this time provokes 3 AoOs, opponent 3 has a CMD of 17 so now you target is 17+2+2=21 (+4 for 2 extra opponents), this time you roll a 19 so all three get AoO's (Ouch!). Luckily for you all 3 missed, now at this point since they all got AoO's you can just step right behind opponent 3 hoping they don't have Combat Reflexes or go it safe and try to use Acrobatics again at 1/2 movement. Knowing you have an ass for a GM you are sure he gave them all Combat Reflexes so you make your roll, You move diagonally right behind opponent 3 this time only provoking 2 AoOs this time your target is 17+2=19 and you roll a 20 making it!
Also if you fail to move through an opponent square since you normally can't move through an opponent with an acrobatics check, I would say you don't go through and you Provoke an AoO, but that one is harder since the rules are less clear there and it is hard to use them to support either case.
Edit: also I would definitely say you don't fall prone, if they meant that to happen they would put that in there.
|
|
This is the way I see it. Your DC is based on moving through a Threatened Square, so for each Threatened square you move through you need to make a roll. So if you move through 3 threatened squares that round using Acrobatics, you need to make 3 rolls. I think this is totally different then 3.5 where you only needed to make 1 roll. Since it is based on a Square and the DC goes up per each additional opponent avoided you only roll once per square based on the highest CMD of the multiple opponents.
I disagree with this. While the Acrobatics section says "you can move through a threatened square without provoking..." There is also the rule that movement through multiple squares only provokes once per opponent. Mommy says one thing; Daddy says another; you still must listen to Mommy and Daddy.
In addition, you can move through a threatened square without provoking an attack of opportunity from an enemy by using Acrobatics.
As an example you are in front of one opponent (1) there is one directly behind that opponent (2) and another directly behind that one (3) that you want to get behind. You go diagonally left which does not provoke since it is the first 5'
What? The first 5' is not negated; it is only negated from AoO if you make a 5' step ONLY, or if you Withdraw. If you're calling this a Withdraw, you open a new can of worms.
I'm not quoting the rest of this, but a couple of comments:
1) As above: you provoke once for movement per encounter. This would be the case if you moved normally. Even if you get caught up in the words, why would it provoke more than once when you are actively trying to avoid provoking?
2) There does appear to be a question working through the boards about multiple or single rolls per threat. I don't have an opinion on it yet, but most of the scenario provided is associated with the threat per square when tumbling idea, which is A Bad Idea.
This is the way I see it. Your DC is based on moving through a Threatened Square, so for each Threatened square you move through you need to make a roll. So if you move through 3 threatened squares that round using Acrobatics, you need to make 3 rolls. I think this is totally different then 3.5 where you only needed to make 1 roll. Since it is based on a Square and the DC goes up per each additional opponent avoided you only roll once per square based on the highest CMD of the multiple opponents.
Your DC is not based on moving through a threatened square, it is based on the CMD of the opponent who you are provoking from and is modified by the number of opponents you have already provoked from. The skill explicitly states for the situation of "moving through threatened area" the DC is "opponent's combat maneuver defense" with an annotation of "...This DC increases by 2 for each additional opponent avoided in 1 round."
I think you are confused, in 3.5 every threatened square you moved through provoked an AoO from every opponent that the square was threatened by. In PFRPG they removed that as they believed it bogged down game play by causing excessive rolls (IIRC the beta thread where it was discussed). Currently in PFRPG, you basically only check the first time the condition happens. If you make the roll, that opponent will be unable to make an AoO against you that round no matter how many squares you move through that would be considered threatened by them. If you fail the roll, the opponent gets to make an AoO the first time you move through a threatened square but will be unable to make subsequent attacks as you move through threatened squares. I placed the page for this information in my initial post, last item of the Base Rules.
Also your example is way off, a 5' step is a very specific condition and you can make no other move actions (without special abilities) in the same round as a 5' step. When moving more than 5' in a round every movement is considered to provoke an AoO (except a withdraw action). I stopped reading after that first error, they way the DC stacks on for each additional opponent, everything you said will be off.
I'm not quoting the rest of this, but a couple of comments:
1) As above: you provoke once for movement per encounter. This would be the case if you moved normally. Even if you get caught up in the words, why would it provoke more than once when you are actively trying to avoid provoking?
Almost ;) If it were once per encounter, AoO's would truly be worthless as they are written. You provoke only once per opponent in a round.
2) There does appear to be a question working through the boards about multiple or single rolls per threat. I don't have an opinion on it yet, but most of the scenario provided is associated with the threat per square when tumbling idea, which is A Bad Idea.
After staring at the rules and jumping all over the pdf's, I'm fairly confident in my initial post tonight regarding RAW. Acrobatics have a great deal in common with the Stealth wording now that I've been digging through things. Both are linked to some sort of movement action (part of a movement, though 5' step is useless for acrobatics) and both restrict the movement they are associated with (half normal movement without adjusting the DC). The way they have set it up now, the only threatened square that is of any consequence is the intial threatened square for each opponent, as they cannot make attacks for your movement after that.
hi there,
Question; attempting to move through a hostile occupied square from an adjascent square, as discussed above requires an acrobatics check to succeed(established) but wouldnt a second acrobatics roll be needed to avoid AoO from leaving a threatened square?(the start point), and if the attempt fails(for passing through occupied square)and you remain where you started,-provoking an AoO for the failed attempt, the second roll would not occur(because you technically didnt leave the starting square, then attempted to move the remaining 5' of your movement (re; skylancer4's point #4 above,)you would indeed draw an attack of op, as the first AoO was for the failed move through, NOT for leaving the threatened square, which are different actions drawing AoO??
so
1)If successful on moving through occupied square with first acrobatics check still requires second acrobatics check to avoid AoO for leaving threatened square2)after failed acrobatics check to move through will still draw AoO if use remaining movement to leave threatened square
The PFRPG rules changed the way AoO's occur for movement. The new rules only allow for 1 AoO for movement in a round by any single opponent.
1) No (well maybe), seeing as the initial roll is successful and is a movement based AoO you wouldn't need to roll a second time. The initial square into the occupied square was the "movement provoked AoO" and is the only thing that would need to be checked for against any single threatening opponent.
The Maybe. If moving through the opponents square provokes from ANOTHER opponent you would check your acrobatics roll for that particular movement action against the CMD (+ DC modifiers) of the new opponent.
2) No (assuming just the opponents who threatened from the initial move), the failed roll means you provoked an AoO, again as that is a movement based AoO you don't provoke again because of the rule restricting AoO's by movement.
|
|
Almost ;) If it were once per encounter, AoO's would truly be worthless as they are written. You provoke only once per opponent in a round.I'm not quoting the rest of this, but a couple of comments:
1) As above: you provoke once for movement per encounter. This would be the case if you moved normally. Even if you get caught up in the words, why would it provoke more than once when you are actively trying to avoid provoking?
Yeah. I know the rule. A brain fart resulted in the wrong word coming out. Thanks for the correction.
The PFRPG rules changed the way AoO's occur for movement. The new rules only allow for 1 AoO for movement in a round by any single opponent.
Almost ;) This was the rule in 3.5 as well; it isn't changed.
Almost ;) This was the rule in 3.5 as well; it isn't changed.
!!! You are right, was late >.<
I too think that using CMD as the DC for acrobatics has made it nearly impossible to succeed.
Back in 3.5, Tumbling was too easy. At level 5 you could have enough at tumbling skill to never suffer a AoO from moving, independent of who was your foe.
Now however it's way too difficult. Since I can't garantee I'll succeed, I'll end up not risking to move, because if I fail and suffer a AoO, then I'll probably get tripped and tha will start a horrible chain reaction. It's just not worth the risk. I've made this chart to show how hard it is:
Moving "through" a threatened square (Half Speed) ---- Average DC (Enemie's CMD) ----- Average Acrobatic Skill (Trained)
Level 05 ------------------------------------------------------------------------- 22 -------------------------------- 11 (50% Success)
Level 10 ------------------------------------------------------------------------- 32 -------------------------------- 17 (30% Success)
Level 15 ------------------------------------------------------------------------- 42 -------------------------------- 24 (15% Success)
Level 20 ------------------------------------------------------------------------- 52+ ------------------------------ 29 ( 0% Success)
Moving "through" a Enemie's square (Half-Speed) ---- Average DC (Enemie's CMD +5) ----- Average Acrobatic Skill (Trained)
Level 05 ------------------------------------------------------------------------- 27 -------------------------------- 11 (25% Success)
Level 10 ------------------------------------------------------------------------- 37 -------------------------------- 17 ( 5% Success)
Level 15 ------------------------------------------------------------------------- 47 -------------------------------- 24 ( 0% Success)
Level 20 ------------------------------------------------------------------------- 57+ ------------------------------ 29 ( 0% Success)
Moving "through" a threatened square (Full Speed) ---- Average DC (Enemie's CMD +10) ----- Average Acrobatic Skill (Trained)
Level 05 ------------------------------------------------------------------------- 32 -------------------------------- 11 ( 0% Success)
Level 10 ------------------------------------------------------------------------- 42 -------------------------------- 17 ( 0% Success)
Level 15 ------------------------------------------------------------------------- 52 -------------------------------- 24 ( 0% Success)
Level 20 ------------------------------------------------------------------------- 62+ ------------------------------ 29 ( 0% Success)
I've been trying to come up with a alternative to CMD, since it's mathematically incompatible with skill checks.
Skills add +1/level +1 Abil Mod +3; (Items that give competence bonus to acrobatics don't normaly work for this)
CMD adds +1/level for warriors, +2 Abil Mod + a number of different bonuses (Deflection, Dodge, Spells, etc)
And it also makes little sense involving the foe's Defense when you're trying to avoid his attack. What does his ability to dodge has to do with someone trying not to get hit by him?
The things I think are important:
- AoO should not be easily avoided. They are a important asset to warriors to prevent foes from running away from them.
- The foe's "Attack Power" should be considered. It should be harder to avoid a lvl 20 Fighter then a lvl 5 Wizard AoO. A fixed DC won't do.
- Keep things Simple. We don't want to slow down the game play.
- I want to be able to do acrobatis while I fight. If it's too hard, that is taken away from the game.
We came up with this concept which has beem working well so far:
For every 4 points you have in Acrobatics, you gain +1 Dodge bonus to AC agains Attacks of Opportunity caused when you move out of of within a threatened area when you Tumble as part of your movement. You need to have at least 4 ranks in Acrobatics to gain this benefit. You Tumble at half your speed, unless you take a -4 penalty to your AC. You cannot tumble to improve your AC while moving past your foes if your speed is reduced due to carrying a medium or heavy load or wearing medium or heavy armor. If an ability allows you to move at full speed under such conditions, you can use Tumble in this way. You can use Tumble in this way while prone, but doing so requires a full-round action to move 5 feet, and you suffer a -2 penalty to your AC.
It's quite simple, which speeds up game play. There's no more avoiding the AoO, instead you just get a Dodge bonus to your AC. This way EVERYTHING is accounted for, the Foe's ability with his weapon, any spells and other bonuses he has to improve his attack, any spells and bonuses you have to improve your defense, if it's a normal attack you'll get to use your normal AC, if it's a touch attack you'll use your touch AC, if you were already easy to hit, now you're a little harder to hit, if you were already hard to hit, now you're even harder, every variable is included which makes it very realistic. It works pretty much like the Mobility feat.
If you wanna move though an enemie's square, you take a -2 penalty to your AC, but he'll still get to make only one AoO agains you. If he does hit you, you didn't get past him and you stop your movement on the closes legal square you came from adjacent to him.
If you are Tumbling through multiple foes, for each AoO you have already suffered for moving this way in this round, you suffer a -1 penalty to AC agins your next AoO also for moving this way.
As for the combat modifiers, they now give penalties to AC like this:
-2 to DC ----- -1 to AC
-5 to DC ----- -2 to AC
-10 to DC ----- -4 to AC (earthquake)
We're still adjusting these number, but so far it's become a realiable option.
Please, share your thoughts about this, if you also find the CMD rule questionable, and if not, why.
BTW, with the official rule, I think you roll once for every enemy you pass through agains their CMD, and increase the DC by +2 for every next enemy you try to pass, in this round.
Oh yes, and as a flavor, we implemented if the AoO is a Crit with a natural 20 roll on the d20 while you are Tumbling then you fall prone. After all, if you're hit like a sledge hammer while you are somersalting, makes sense that you fall prone. Without that, it would be as if you could never fail a tumble, but we don't want to throw people prone all the time, since it's a powerfull and complicated debuff, so a 5% chance (less actualy, since you have to confirm the crit) seems like a good chance.