[3.5] Concentration/Tumble

[Necron]

I've been considering creating a house rule for an upcoming game with regards to a few Skills. Specifically Concentration and Tumble. I personally feel that both Casting Defensively and Tumbling DC's should be more reflective of the engaged targets abilities.

I want to incorporate opponent's BAB into the DC equation.

Tumble
Around DC = 10 + opponent's BAB + size disparity + 2 additional checks
Through DC = 20 + opponent's BAB + size disparity + 2 additional checks

Size disparity effects the DC when a tumbling character is not the same size as the opponent he's tumbling around/through. Basically the character gets a bonus (-4 to DC) for each category smaller, and a penalty (+4 to DC) for each category larger.

It's easy for the Human Rogue to tumble through the Huge Giants square. But it's more difficult for him to tumble through the Tiny Pixies square.

Concentration
Casting Defensively = 10 + Spell Level + opponent's BAB

Obviously this makes it MUCH more difficult (if not impossible) to cast in the face of high-level encounters.


So where does this proposed system fail? Is it unfair to force PC's to deal with this? Does it force people to "waste" skill points excessively?

I value your input.


~EDIT
I added some stuff about size disparity to Tumbling

[Eloel]

It fails not because it's a bad system, but because it works similar to truenaming. You're not facing 20HD creatures at ECL20, you're facing something like 40HD

Example:
Wyrm Black Dragon is CR20. With 34HD and thus 34BAB. That's 14 more than predicted for both Tumble and Concentration, that hurts. (doable, just not practical)

[Thespianus]

I like it.

It makes it a bit easier for the tumblers at early levels, and ensures that you can't forget about your Tumble skill once you reach 15 in base bonus.

Also, it makes it a bit harder for the casters.

So, it's balancing and adds "realism". I like it.

The only thing might be that Mosnters don't normally have "BAB", do they? So you might have to go with HD instead of BAB för monsters, right?

EDIT: My inexperience with high level games shines through. Add Half the monster's HD to the Concentration check, instead of the full number of HD. ;)

[Eloel]

The only thing might be that Mosnters don't normally have "BAB", do they? So you might have to go with HD instead of BAB för monsters, right?

They do, depending on their Type.

Dragon Type
# Base attack bonus equal to total Hit Dice (as fighter).

Elemental Type
# Base attack bonus equal to ¾ total Hit Dice (as cleric).

.
.
.

Add Half the monster's HD to the Concentration check, instead of the full number of HD. ;)

So vs a Balor you need 20 + spell level concentration, and vs a Dragon you need a 27 + spell level, while they're both around same power? Err....

(No, don't use CR for it, it sucks more than a vacuum cleaner.)

[Thespianus]

(No, don't use CR for it, it sucks more than a vacuum cleaner.)

The BAB would be better, as it kinda indicates the opponents fighting skills. The reason I had for going with HD was that I thought monsters lacked BAB.

[Curmudgeon]

So where does this proposed system fail? Is it unfair to force PC's to deal with this? Does it force people to "waste" skill points excessively?

It fails by being totally impossible to use these skills as designed. BAB isn't a reflection of enemy capability unless you're going up against enemies built primarily with class levels. Monster BAB = HD tends to go up much faster. Remember, you only get to improve skill ranks by 1 per level, and enemies' BAB for reasonable single CR-appropriate monsters can go up twice that fast.

Plus there's the whole unknown to contend with. Without ranks in all the Knowledge skills related to different monster types (and there are six of those) the PCs can't hope to even know if they have a chance to succeed. That's a further skill cost, when you've already made the investment have poor return.

Basically, you've made the wisest course to be: put zero ranks in these skills, because the investment isn't worthwhile.

[Necron]

Ooo, I did overlook that monster BAB does get jacked well passed 20.

So how do I incorporate a fair system to make both of these skills more difficult depending on opponent's?

I like the idea of making casters have to think before they cast in the face of a masterful combatant. But I guess there isn't a quick and easy solution to this. Cause touch spells seem to get the kick in the knee for these changes.

Feels like in order to really spice it up with the players I'll just have to make Mage Slayer much more common.

[Thespianus]

Remember, you only get to improve skill ranks by 1 per level, and enemies' BAB for reasonable single CR-appropriate monsters can go up twice that fast.

But, with skill ranks, you can start with 4 at level 1, you gain your attribute bonus as well (and the Dex attribute bonus for a tumbler goes up pretty high at higher levels) and the base value needed to succeed has been made lower.

It makes Tumbling more dangerous at higher levels, yes, but it defeats the silliness that is the static DC.

I would like to see the opponents level or BAB or HD, or whatever somehow factored into the DC calculation, but I can also see how it might be tricky to get it right.

It just seems silly that a high level caster can always succeed in casting on the defensive no matter what hordes of creatures surround him.

[Epinephrine]

Looks fine to me.

Don't worry about high level people, if casting is important to a 20th level wizard he'll have an item with +15 Concentration, and he'll have maxed his ranks, too.

Likewise with Tumble - if you want to be maneuverable in combat you'll simply trick out your tumble skill with items.

We use very similar rules in our campaign, and it's working fine. The tumbling monk is still very tough to stop from moving about, and the casters are still very tough to shut down - but you don't get freebies, and some enemies do present risks, as they should. The bard has an investment in tumble and can duck past less impressive folks or tumble through a caster's square, but won't be tumbling away from a dragon, which is as it should be.

[Thespianus]

LThe bard has an investment in tumble and can duck past less impressive folks or tumble through a caster's square, but won't be tumbling away from a dragon, which is as it should be.

This is exactly what I like about this way of calculating Tumble DC.

Sure, it may make it hard for the players to know the exact DC of the Tumble roll, but.. hey, so's the Open Lock DC or Disable Device-DC anyways, right?

[Necron]

We use very similar rules in our campaign, and it's working fine.

Would you be willing to post the rules that your group uses? Seems like you've play tested it and it's a functional model to compare the proposed system to.

[Necron]

Oh, and on further consideration I'm going to tweak the Tumble DC slightly to account for Size disparity. I think it would still be easier for a small creature to move around/through a larger creature.

So I'll probably include a size modifier depending on the disparity of sizes.

So Small's would get a -4 DC against Medium. -8 DC against Large... etc.

The inverse would also be true, it's harder for a larger creature to tumble through a smaller creatures square.

[Pharaoh's Fist]

I'd go 10+1/2 BAB + spell level as the DC for concentration, which I beleive works out ok.

10+ BAB, with size modifiers as appropriate, for tumble.

[Clementx]

Or you could realize that larger creatures already include their own penalty against tumblers: it requires more squares of movement to escape their threatened area, cross their space, or move into flanking position. The average tumbler either has to take the -10 to go at full speed or invest heavily in speed bonuses. This keeps the novice tumbler less efficient at moving, which is the real goal of the maneuver. It doesn't matter how easy it is to avoid the AoO if you can't reach your destination fast enough.

[infinitypanda]

One problem with your size disparity is that a human gets a -8 to tumble through a square with a tiny creature. That's a -8 to tumble through a five foot square only occupied by a two foot tall creature. The problem with this is that smaller creatures take up less space relative to the size of the area you tumble through, so the DC should be lower.

Really, if you want to use size disparity I think it should be -4 per size category in either direction.

[Epinephrine]

Would you be willing to post the rules that your group uses? Seems like you've play tested it and it's a functional model to compare the proposed system to.

Sure - initially we used 12+Ref save for the tumble DC (making it reflex based made some sense), but we switched a while back to:
15+BAB to tumble without provoking,
20+BAB to tumble through an occupied square.
We add +2 for each subsequent check, you check for each person threatening you, can choose the order.
If you succeed by more than 5 you can move full speed while tumbling.
An additional rule we added was that monks count as having full BAB (so it's 15+monk level) for the purpose of tumbling by them.

Concentration we had as 10+BAB+spell level. We liked that it scales as fast as the enemy levels, so you had to pump points into it, and likely invest in some Concentration items -Combat Casting was a useful thing; all mages took it. It seemed actually pretty easy for casters to make their checks, just eating up skill points - after all, Con is generally a pretty good stat, a Con item is nice for HP, Fort save, and for Concentration, a +5 Concentration item is only 2,500gp (IIRC), and Combat Casting for +4.

When we made the jump to Pathfinder (which has no concentration skill) we adpoted the Pathfinder concentration check - casters use d20+level+casting mod against a DC of 15+2*spell level. The 2*spell level scales as fast as a skill like concentration would (or as fast as levels do), but since you add your casting attribute bonus (which you'll be pumping anyway) you do get better at it. This had the advantage of not costing a caster any skill points, but keeping the big spells difficult to cast when threatened.
The opponent's BAB doesn't factor into it, though, which is unfortunate in one sense - but it is easy to calculate, and not min-max fodder. We don't add to the DC for multiple foes, though we do add to the DC if you would be vulnerable to losing your Dex bonus against any foes (essentially a +2 DC if you are flanked or facing an invisible foe).

[Riffington]

The reverse option also works. You provoke attacks of opportunity with every movement through a threatened square as normal. But if you are tumbling, you may replace your AC with your Tumble modifier + 10. Add 4 to this if you have mobility. Simple and saves time.

Now for casting defensively, you have to decide what it is that defensive casting really does. Is it that you're not really getting in the enemy's sword. If so, then you can do the same thing with Concentration (with bonus for combat caster). Arguably in this case you want to use your Dex Modifier instead of your Con. On the other hand, if it's that you're actually leaving no openings, just that spells are hard to cast that way, you don't want the enemy's BAB to be relevant at all. But it soudns like thats not your preferred interpretation.

[jiriku]

Instead of adding base attack, you could oppose it with an enemy's attribute bonus (say, Dex for tumbling and Str or Dex for Concentration, depending on whether opponent has weapon finesse or not). This gives you a scaling value, but the number will scale much more slowly than base attack.

However, if you're really looking for advice, I'd say just don't mess with it. There isn't a balance issue in the use of these skills, so you're just after realism. Trying to houserule D&D into a realistic system is both a never-ending task and a lost cause. You'd be better off investing your time into developing a realistic campaign setting than developing realistic house rules.

[Epinephrine]

However, if you're really looking for advice, I'd say just don't mess with it. There isn't a balance issue in the use of these skills, so you're just after realism. Trying to houserule D&D into a realistic system is both a never-ending task and a lost cause. You'd be better off investing your time into developing a realistic campaign setting than developing realistic house rules.

I think that it does affect balance.
With tumble being harder a mage type can't tumble away from a fighter (maybe not many bothered, but with a positive dex modifier and a skill item it wouldn't be hard for even a wizard to grab a few ranks cross-class and hit the +14 Tumble needed); with defensive casting being harder the enemy can't simply stand and cast as safely. It might seem like it's only a concern for realism, but it does change the way things play out (at least, in my experience).

[lsfreak]

DC15 Tumble check gets you a +4 to your AC versus one attack, +4 more for every 10 of your check. No matter what they get to make the AoO, it's just a matter of whether or not it hits.

Same with Concentration, DC15 for a +4AC, +4 for every 10 after that.

Mobility and Combat Casting let you sacrifice one of your own AoO and an immediate action to dodge an AoO that should have hit (provided the AoO was provoked by movement/casting).

Granted, the people I've played this with don't optimize very much.

[Necron]

Pharaoh's Fist
The 1/2 BAB for Concentration might be more reasonable.

Clementx
You are spot on, I didn't realize the space larger creatures take up makes things even more difficult (generally adding another -10 to the check for an accelerated tumble). Hrmmm... the intent of my changes were to spice up generally similar sized opponents.

infinitypanda
I actually think it would be easier for a tiny creature to smack you while you're moving through it's space. It's not that it's hard to move through the space, it's hard to move through the space and not get whacked.

Epinephrine
Thanks for your rules. I'd probably not include the extra about Monks... I tend to avoid adding exceptions. I've been really leery about using anything Pathfinder just yet (though I've recently considered changing to using the Races and Sorcerer over the existing 3.5).

Riffington
That's kinda interesting, it's not a bad thing to consider.

jiriku
I'm looking for simple... The conditionals you've cited are just too clunky for my uses. I was just trying to change the formula a little to make things more difficult for some.

Isfreak
Interesting I guess. It's definately moving away from what I wanted though. I was really just looking for a way to spice up the DC's for Concentration/Tumble, not to revamp the system.


Last Thoughts
So at this point I'm debating even bothering adjusting the system. The point was that I wanted casters to have more of a challenge when confronted with skilled attackers. Likewise with the tumblers. The flat DC's just kill me that they don't scale for more difficult opponents... Typically in my campaigns players just shoot for the static DC and then don't bother.

I guess maybe I'm going overboard given that the extra skill points players save by using the regular system allows their characters to be more versatile then if I imposed these changes.

So I'm going to just scrap the idea for now. Thanks for your input everyone.

[Fluffles]

Sure - initially we used 12+Ref save for the tumble DC (making it reflex based made some sense), but we switched a while back to:
15+BAB to tumble without provoking,
20+BAB to tumble through an occupied square.
We add +2 for each subsequent check, you check for each person threatening you, can choose the order.
If you succeed by more than 5 you can move full speed while tumbling.
An additional rule we added was that monks count as having full BAB (so it's 15+monk level) for the purpose of tumbling by them.

Concentration we had as 10+BAB+spell level. We liked that it scales as fast as the enemy levels, so you had to pump points into it, and likely invest in some Concentration items -Combat Casting was a useful thing; all mages took it. It seemed actually pretty easy for casters to make their checks, just eating up skill points - after all, Con is generally a pretty good stat, a Con item is nice for HP, Fort save, and for Concentration, a +5 Concentration item is only 2,500gp (IIRC), and Combat Casting for +4.

When we made the jump to Pathfinder (which has no concentration skill) we adpoted the Pathfinder concentration check - casters use d20+level+casting mod against a DC of 15+2*spell level. The 2*spell level scales as fast as a skill like concentration would (or as fast as levels do), but since you add your casting attribute bonus (which you'll be pumping anyway) you do get better at it. This had the advantage of not costing a caster any skill points, but keeping the big spells difficult to cast when threatened.
The opponent's BAB doesn't factor into it, though, which is unfortunate in one sense - but it is easy to calculate, and not min-max fodder. We don't add to the DC for multiple foes, though we do add to the DC if you would be vulnerable to losing your Dex bonus against any foes (essentially a +2 DC if you are flanked or facing an invisible foe).

Third Eye Concentrate (MIC) is +10 to concentrate, 10k gp, and takes up the face slot.