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An Essay by Justin Alexander

One of the nits that seems to get perennially picked in D&D is the Tumble skill. Specifically, the uses of the skill which allow a character to avoid attacks of opportunity: The DC 15 check to avoid attacks for moving through threatened areas and the DC 25 check to tumble right through an opponent's space.

There are generally understood to be two shortcomings to these rules:

1. The game already makes it relatively difficult to control territory. For example, there is no effective way for a single person to guard a 10' wide hallway -- no matter how skilled they are and unskilled their opponents are. The Tumble skill exacerbates this because now you can't even control the space you're standing in: Say the PCs want to prevent someone from reaching the Lever of Doom at the end of a hallway -- it doesn't matter how many demigods you cram into the hallway, a 1st level tumbler can still move past them like water through a sieve.

2. The idea that some skill in tumbling would allow you to dextrously move past a slower and clumsier opponent is not problematic in and of itself. The problem is that the DC for check is flat: It would be fine if the 5th level rogue could tumble past a whole brigade of 1st level warriors, but it shouldn't be possible for that same rogue to tumble past Cyrano de Bergerac or Benedict of Amber.

Essentially, the Tumble skill needs to somehow take the skill of the person you're tumbling past into account.


Over the years I have seen several attempted solutions (and attempted many myself). These include:

1. Opposed tumble checks.
2. The tumble check is opposed by a Reflex saving throw.
3. The tumble check replaces your AC.
4. The tumble check is added to your AC.
5. Add your tumble bonus (sans Dex) to your AC (either with or without a flat-DC check).
6. Add the level of the character you're tumbling past to the DC of the check.
7. Add the BAB of the character you're tumbling past to the DC of the check.
8. Add the melee attack bonus of the character you're tumbling past to the DC of the check.
9. The tumble check is opposed by a melee attack roll. (If the target succeeds at the opposed check, a new attack roll is made to resolve the AoO.)
10. A flat-DC check grants you a flat +4 dodge bonus to AC. (The Mobility feat either makes the check unnecessary or stacks.)


None of these are entirely satisfactory, in my opinion. The reasons include:

1. Tumbling is not a required skill for being a highly-skilled swordsman. Not only doesn't it make sense for my ability to hit your with a sword to be dependent on my ability to (literally) jump through hoops, it also doesn't solve the inherent imbalance you're trying to correct: The tumbler will still be able to tumble past the finest swordsmen in the world (since it's unlikely they've taken ranks in Tumble).

2. This mitigates the problem better than an opposed Tumble check (since Reflex saves improve automatically). And although Reflex saves still aren't tied to melee prowess, the conceptual match is slightly better: It makes sense that quick reflexes would allow you to react quicker to a tumbler. But this solution doesn't actually fix the game balance issues: Saving throws simply don't advance as quickly as skill ranks do. The tumblers still outstrip the abilities of the fighters, it just takes them slightly longer to do it.

3. Tumbling should never make you easier to hit than if you just casually strolled by the person you're attacking. It is relatively trivial to come up with situations where replacing your AC with your Tumble check would result in precisely that.

4. One interesting facet of the 3rd Edition rules is that a character's AC is, essentially, a special case of the central resolution mechanic in which you take 10 and then add your various bonuses. (In fact, many variants exist where you roll a d20 instead of effectively taking 10 to determine your AC against any particular attack.) But when you think of AC in this way, the problem with this solution immediately becomes apparent: In addition to your own tumbling skill, you're also adding a second d20 roll to your total. This is obviously not balanced.

5. But simply adding your Tumble bonus doesn't work, either. It eliminates that second d20 roll, but you're still faced with the fact that this would become a huge bonus. Consider the fact that the game is obviously balanced so that two characters of the same level both have at least a decent opportunity to hit each other. Tacking on a +20 bonus to AC obviously throws that out of whack. If that doesn't convince you, simply consider the fact that a magic item conferring a +10 bonus to Tumble costs roughly the same as a +3 bonus to AC.

6. Adding the level of the character you're tumbling past to the DC of the check at least takes some measure of the skill of the opponent you're facing. But level is only proximate to combat, and the system begins suffering some real problems when you try to use it with monsters (many of which have HD higher than their CR).

7. Adding the BAB, on the other hand, is a much better solution. I would recommend lowering the base DCs slightly to compensate in the tumbler's favor here (so the checks would DC 10 + BAB and DC 20 + BAB). The only problem with this is that BAB, while a better proximate of combat prowess than level, is still only proximate: There are many, many things which improve your ability to make an attack. But this is definitely a workable solution.

8. Adding the full melee attack bonus, on the other hand, doesn't work. The problem simply becomes that the resulting DCs end up being far too high to be reasonable for a character of the same level. You can mitigate this somewhat by stripping away most or all of the base DC of the check (so the DCs become equal to the melee attack bonus and the melee attack bonus + 10 for the two checks), but this only mitigates the problem. And, at low levels, it results in check DCs which are too low.

9. This is the solution proposed by Monte Cook in ARCANA EVOLVED and then later picked up by Mike Mearls in IRON HEROES. Cook makes the basic "avoid AoO" a straight opposed check, while effectively giving the tumbler a -5 penalty on a check to tumble through someone's space. Cook and Mearls are both savvy game designers and, as one might expect, this is probably the best solution we've looked at so far: It turns out that attack bonuses and the skill bonus of a specialist tend to stay within reasonable distance of each other at any given level. And by making the check a gatekeeper for the actual resolution of the AoO (the check doesn't determine whether the AoO succeeds or not, it determines whether the AoO can be attempted), Cook makes sure that tumbling never makes it more likely for the tumbler to be hit.

The only criticism of this method is that it essentially doubles the amount of time it takes to resolve the action. This is not necessarily the end of the world, but whenever you add a die roll to the game you're slowing it down. Slow it down enough and it's no longer fun to play.

10. This is a fairly elegant solution, but suffers from two shortcomings. First, it fails to address the "move through their space" element. Second, the lack of scaling with skill has simply been moved from the person being tumbled past to the person doing the tumbling: No matter how skilled you are at tumbling, you still get nothing more than that flat +4 bonus to AC. Tying the size of the AC bonus to the result of the Tumble check can solve the second problem, but only clumsily or through the use of a chart look-up (neither of which, in my opinion, are desirable).


So, taking all of that into consideration, is there a solution which works? For me, a successful rule would need:

1. To take into account the skill of both the tumbler and the person being tumbled past. Highly skilled swordsmen should be tougher to tumble past than neophyte warriors; highly skilled tumblers should be better at tumbling past people than amateur acrobats.

2. Never result in the tumbler being easier to hit than if they hadn't tumbled.

3. Be simple to use and easy to remember. And, to that end, consistent with other skill checks. (In general, if three or four different tasks use the same mechanic, it's easier than if those tasks each use different mechanics.)

4. Minimize the number of rolls needed to resolve the action.


I'm going to make the rather radical suggestion that part of the problem in trying to solve this problem is that there are actually multiple actions trying to be resolved simultaneously. In reality, there are three things these Tumble checks are attempting to handle:

1. The ability to move around the battlefield quickly and nimbly (minimizing the risk posed from people taking shots at you as you run by them).

2. The ability to dextrously move through someone's space.

3. The ability to nimbly avoid a specific attack aimed at you.

I'm going to sugggest that the solution is to split these different actions up and resolve them independently of each other.

TUMBLING MOVE: By making a Tumble check (DC 15) you gain a +4 dodge bonus to Armor Class against attacks of opportunity caused when you move out of or within a threatened area. You can move up to half your speed without penalty. You can move at your speed by accepting a -10 penalty to this check and you can run by accepting a -20 penalty to this check.

TUMBLE PAST: You can attempt to tumble through an opponent's space as part of normal movement. Because you are entering an opponent's space, this provokes an attack of opportunity from the opponent. You must make a Tumble check (DC 25). If the attack of opportunity is successful or the Tumble check fails, you move back 5 feet in the direction you came, ending your movement there. Otherwise, you move through the opponent's space and can continue your move normally.

AVOID ATTACK OF OPPORTUNITY: When you are hit as a result of an attack of opportunity you provoked, you may use an attack of opportunity or swift action to attempt a Tumble check to negate the hit. The hit is negated if your Tumble check result is greater than the opponent's attack roll. (Essentially, the Tumble check becomes your Armor Class if it is higher than your regular AC.)


This solution keeps most resolutions to a simple skill check vs. a flat DC (the easiest of all possible skill checks), but it never negates the opponent's ability to interfere with the tumble. In one key regard it borrows Cook's solution of opposing the Tumble check with an attack roll, but by borrowing from the Mounted Combat feat mechanic of negating a hit it simplifies Cook's solution: Instead of two separate resolutions, there is essentially only one resolution point (nobody is ever asked to roll more than a single check to resolve the action).

We've also made a successful use of this ability more useful, because it actually uses up the opponent's attack of opportunity. As a result, the character must burn a limited resource (either an attack of opportunity or a swift action) in order to perform the attempt. Any character with basic training in tumbling can attempt to dodge their way nimbly through combat (by making a flat DC check to receive a bonus to AC), but if a character wants to be able to really dance through a mob of opponents, they should pick up the Combat Reflexes feat.

Those flat DCs also hide another useful design feature: Eventually the tumbler won't have to actually make those checks. At that point, the only check which becomes important is the opposed check to negate the hit. This further speeds up gameplay while satisfying our design goals.

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