Are these changes to SR and miss chances workable?

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Emerald
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Are these changes to SR and miss chances workable?

Post by Emerald »

A friend of mine will be running a mid-level Underdark-focused game starting in a week or so, and because of the expected prevalence of spell resistance and concealment (all of the PCs and many of the enemies will be drow, and he's adding blur to the list of drow racial SLAs) he was thinking of houseruling SR and miss chances to make them faster to resolve and hopefully simpler to work with. He felt that converting them to flat AC and save bonuses or the like would leave them too weak, so he came up with something else and sent me his proposal; I wanted to run them by the Den and get your take on them. Proposed changes are summarized below, my comments are in [brackets].

Miss Chances

Instead of being a percentage roll, concealment and other miss chances are represented by a number between 1 and 20, inclusive, found by dividing the percentage by 5, so 50% is "concealment 10" etc. When an attacker rolls that number or less on a d20, the attack is an automatic miss, e.g. concealment 1 doesn't have any effect past the usual auto-fail-on-a-1 rule, concealment 10 means you auto-fail half the time, and so on.
[I suppose that works; at least it's a lot faster than rolling d% for every attack.]

Cover grants a miss chance (improved cover = cover 10, cover = cover 5) instead of an AC bonus. Other effects of cover are unchanged.
[I don't know if cover 10 would be sufficiently equivalent to +8 AC, but it would certainly help characters with very low AC whose AC would suck even with the bonus.]

Shields grant a cover miss chance equal to double their normal shield bonus, so a heavy shield grants cover 4 and so on. When fighting defensively, using total defense, using Combat Expertise, or taking other special defensive actions with a shield, you can "flip" the bonus to make the other end of the d20 range automatically miss--e.g. if you have cover 4 from your shield, when fighting defensively you may choose to make a 17 or more auto-miss instead of a 4 or less.
[He didn't specify whether this cover is instead of or addition to the AC bonus shields normally grant; if it's the latter, I like that this makes shields more attractive. The cover flipping thing is kind of confusing at first glance, but it helps against crits, and something that might make total defense ever worth considering is okay in my book.]

You can never have a miss chance from a single effect or circumstance greater than 10. Miss chances come in three varieties--concealment, cover, and "other" (e.g. the miss chance from blink)--and each doesn't stack with miss chances of the same type; if you have more than one of cover, concealment, and "other" miss chances, you take the highest miss chance plus 1/2 of the second-highest plus 1/4 of the third-highest as the final miss chance.
[Makes sense to me, and prevents easy abuse.]

Spell Resistance

Like miss chances, SR is now a number from 1 to 20. SR has two effects: First, if an effect allowing SR wouldn't allow a save, a creature with SR may make a save against it normally. Second, when making a save against an effect allowing SR, the creature may treat the number rolled on its save as its SR value if it rolls lower--e.g. a creature with SR 5 treats any roll of natural 1 to natural 4 on the d20 as a 5 instead. As a side benefit, this means that creatures with SR 2 or higher don't auto-fail saves against spells allowing SR.
[Definitely faster than rolling a separate CL check, and the non-autofail aspect is a nice perk, but it might make SR too effective.]

Because the current categorizations are inconsistent and in some cases BS [he specifically mentioned the orb spells as deserving to be SR: Yes Evocations], spells will allow SR if and only if they meet one of the following criteria:
--"Target" or "Effect: Ray" spells
--AoE spells with instantaneous durations that actively and directly affect creatures (so e.g. alarm, disjunction, or detect poison wouldn't qualify)
[I like the standardization of whether SR affects things, but the second category is still a bit fuzzy for my liking.]

Because SR now simply modifies saves, you can choose to waive your SR against a given effect as a non-action as part of choosing to fail a save.
[Definite like, I houserule away the "drop SR as a standard action" thing anyway.]


Thoughts? Suggestions? Critiques? I'll pass everything along.
jadagul
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Post by jadagul »

My big concern with these is that concealment and miss chances are now completely useless against weaker monsters. So if something hits you on a 2, then concealment 10 is pretty good; but if something only hits you on an 11+, concealment is absolutely and totally useless.

This is mechanically weird, and also leads to the counterintuitive result that hiding or blur is totally useless against mooks.
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Post by Grek »

All of the concealment effects come in increments of 5%. You shouldn't roll a d100 each time, you should roll a d20. If you have 50% concealment, you roll an extra d20 with every attack, and it auto-fails on everything but an 11+.

I have no idea why you would actually roll a d100 to do concealment.
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Emerald
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Post by Emerald »

jadagul wrote:My big concern with these is that concealment and miss chances are now completely useless against weaker monsters. So if something hits you on a 2, then concealment 10 is pretty good; but if something only hits you on an 11+, concealment is absolutely and totally useless.

This is mechanically weird, and also leads to the counterintuitive result that hiding or blur is totally useless against mooks.
You know, I didn't even notice that, since I was looking at it purely from an "optimized level X PCs vs. optimized level X NPCs" perspective without taking summoned critters or undead minions into account. And considering I'm playing in this game as a summoner.... *facepalm*

Would it work better if miss chances chopped off the top range of values by default like in the fighting defensively scenario? i.e. concealment 4 makes 17 and above miss instead of 5 and below, so mooks who need a 18 to hit you are shut down, but someone who hits you on a 2 has a miss chance of 25% (from concealment + natural 1s) which is close enough to the original value. That's still somewhat awkward because you have to translate "concealment X" to "miss on a [21-X] or above," but people do that for crit ranges already and the equivalent to the common 20% and 50% concealments shouldn't be hard to figure out quickly.
Grek wrote:All of the concealment effects come in increments of 5%. You shouldn't roll a d100 each time, you should roll a d20. If you have 50% concealment, you roll an extra d20 with every attack, and it auto-fails on everything but an 11+.

I have no idea why you would actually roll a d100 to do concealment.
I and the other DM usually do roll concealment with d20s, but the purpose of this houserule was to avoid having to make extra rolls altogether.
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Post by Grek »

What does someone with an attack bonus of 5 hitting someone with AC 15 and concealment 7 look like? 10% normal hits, 5% crits and 85% misses?
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Emerald
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Post by Emerald »

Grek wrote:What does someone with an attack bonus of 5 hitting someone with AC 15 and concealment 7 look like? 10% normal hits, 5% crits and 85% misses?
Yep. That person needs a 10 or more to hit. Using the original proposal (concealment 7 = 7 and below miss), that's 45% misses, 55% hits, since the character needs above a 7 to hit anyway. Using the revised proposal (concealment 7 = 14 and above miss), that's 85% misses, 15% hits, since only 10-13 hit. Using standard rules, that's about 65% misses, 35% hits.

So it looks like his original proposal is great against on-level opponents with high attack bonuses, the revised one is great against mooks with low attack bonuses, and neither quite matches the original probabilities, though they're both off by about the same amount. Hmm...Would tweaking it by a half up or down, rounding towards the middle, do better? i.e. first version concealment 7 goes to 7*1.5 round up, or 11, and the second version concealment 7 goes to 7/2 round down, or 3. That would change the probabilities in version 1 to 45% hits (10 and 11 don't hit anymore) and in version 2 to 40% hits. Which means in this particular instance it's closer but not exact, but of course in other scenarios it could be quite different. I'll need to do some number crunching, probably should have done that before.

Does anyone have any other ideas about changing concealment to not require an additional roll while hopefully leaving the probabilities mostly the same?
jadagul
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Post by jadagul »

Well, nothing's ever going to replicate the original chances exactly--you just don't have the same curve of results with 1d20 that you do with 2d20. The question is what you want to do.

The original setup means concealment is useful against enemies with high attack bonuses. So max concealment is really useful against the boss monster who hits on a 2, it's almost useless against and optimized opponent who hits on an 8, and completely useless against anyone who hits less than half the time. In general, this is significantly less powerful than standard concealment. Min concealment--conceal 1--is totally useless against everything, since everyone misses on a 1 anyway.

The "top-down" setup is in general more powerful than standard concealment. Against a monster that hits on a 2 it's basically equivalent to normal concealment; against anything weaker, it grows more powerful, until you get to mooks who were only hitting on a 20 and now can't hit at all if you have conceal 1. A character with conceal 10, which is max, can't be hit at all by a character who'd normally hit half the time; that's crazy powerful. Note you'd also have to do something about crits--taken literally, conceal 3 or so means you can never get critted unless someone has seriously cheesed out his threat range.

If you were perfect at math, really what you'd want to do is figure out what number the attacker needs to roll to hit, figure out how many numbers he's going to hit on, and chop off the top x% of those. That gives you the right answer but only at the cost of a lot of mental math, which is probably more work than just rolling the second die (especially if you roll both dice together).

But that doesn't mean you don't want to go with one of the first two options, depending on the results you want. Among other things, if you're a summoner, option 1 is great for you--your mooks ignore miss chances completely and you're still protected from boss monsters.
Emerald
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Post by Emerald »

jadagul wrote:But that doesn't mean you don't want to go with one of the first two options, depending on the results you want. Among other things, if you're a summoner, option 1 is great for you--your mooks ignore miss chances completely and you're still protected from boss monsters.
Part of the reason I wanted to run this by the Den was that I didn't want my evaluation to be biased by the fact that I'm playing in this game, and playing a minionmancer at that; I'd certainly love for option 1 to be used, but it wouldn't exactly be fair for the NPCs. ;)

As far as I can tell (haven't been able to talk to the DM since I started the thread) he basically wants to get close-ish to the original numbers while being able to resolve everything easily and without extra rolls, perfect fidelity to existing numbers isn't as important. If we can tweak the numbers to the point that mooks and bosses are affected about the same, no builds get shut down by the new version, and it doesn't require extra rolls or tons of mental math, that's what he's going for. If you have any ideas about tweaking the probabilities and fixing the crit issue and so forth, I'm all ears.
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Post by fectin »

Replace cover with a flat AC bonus, if you just want to speed it up. Same with concealment. I'd make them overlap, not stack.
Offhand, hand out +2, +4, +8 for 1/4, 1/2, and 3/4 cover or concealment. if it's a flat miss chance, either decide it's basically cover or concealment (like blur) and round it to the nearest amount, or decide it's funky enough that you need to preserve the original mechanic (like mirror image).
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Post by Emerald »

fectin wrote:Replace cover with a flat AC bonus, if you just want to speed it up. Same with concealment. I'd make them overlap, not stack.
Offhand, hand out +2, +4, +8 for 1/4, 1/2, and 3/4 cover or concealment. if it's a flat miss chance, either decide it's basically cover or concealment (like blur) and round it to the nearest amount, or decide it's funky enough that you need to preserve the original mechanic (like mirror image).
So you don't think it's worth it to try to preserve the whole extra-layer-of-defense AC/miss chance distinction?

And what do you think of the SR idea?
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Post by fectin »

Emerald wrote:
fectin wrote:Replace cover with a flat AC bonus, if you just want to speed it up. Same with concealment. I'd make them overlap, not stack.
Offhand, hand out +2, +4, +8 for 1/4, 1/2, and 3/4 cover or concealment. if it's a flat miss chance, either decide it's basically cover or concealment (like blur) and round it to the nearest amount, or decide it's funky enough that you need to preserve the original mechanic (like mirror image).
So you don't think it's worth it to try to preserve the whole extra-layer-of-defense AC/miss chance distinction?

And what do you think of the SR idea?
I think that preserving the whole extra-layer-of-defense AC/miss chance distinction is incompatable with your stated goal of making miss chances faster to resolve and simpler to work with. The d% roll is already barebones. It's basically just a weighted coin flip; there are no modifiers or anything. The only way to make it simpler is to get rid of the extra check, and the only way to really do that is to roll it into the main attack. If you want to roll it into attack rolls, you basically have two options: AC bonus or attack penalty. They're theoretically the same, but in practice it's much easier to keep track of persistent effects like blur as AC bonuses. Also, players already know how AC bonuses work. You don't have to explain it; just list the bonuses.

I'm less sure on SR, but the mechanics don't seem likely to be any faster.
Within that, they definitely don't seem likely to speed up your game specifically. You'll lose a bunch of time re-explaining the rules during play, each save will take longer (that extra check does take time, and discussing it takes more), and you'll bog down figuring out what effects the new saves have on save=no spells. (e.g., what happens if someone "saves" against enervation? Is that save:half or save:no effect? What about timestop? Wish? Those particular ones might not come up, but they should show how that plan breaks).
Tossing out the book entries on SR seems unlikely to be good for your game. The impulse makes sense, but at least you could look it up right now.
Edit:clarified.
Last edited by fectin on Wed Jul 13, 2011 4:38 am, edited 1 time in total.
Emerald
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Post by Emerald »

fectin wrote:I think that preserving the whole extra-layer-of-defense AC/miss chance distinction is incompatable with your stated goal of making miss chances faster to resolve and simpler to work with. The d% roll is already barebones. It's basically just a weighted coin flip; there are no modifiers or anything. The only way to make it simpler is to get rid of the extra check, and the only way to really do that is to roll it into the main attack. If you want to roll it into attack rolls, you basically have two options: AC bonus or attack penalty. They're theoretically the same, but in practice it's much easier to keep track of persistent effects like blur as AC bonuses. Also, players already know how AC bonuses work. You don't have to explain it; just list the bonuses.
Good points all. I took a look at SWSE the other day and noticed that they turned miss chances into AC bonuses there as well, and it seems to work well enough there. I suppose AC bonuses really are the best way to go.
I'm less sure on SR, but the mechanics don't seem likely to be any faster.
Within that, they definitely don't seem likely to speed up your game specifically. You'll lose a bunch of time re-explaining the rules during play, each save will take longer (that extra check does take time, and discussing it takes more), and you'll bog down figuring out what effects the new saves have on save=no spells. (e.g., what happens if someone "saves" against enervation? Is that save:half or save:no effect? What about timestop? Wish? Those particular ones might not come up, but they should show how that plan breaks).
Tossing out the book entries on SR seems unlikely to be good for your game. The impulse makes sense, but at least you could look it up right now.
Edit:clarified.
I should have mentioned that it's a save negates, just like existing SR negates the spell entirely; time stop affects just the caster (who presumably would waive the SR) and wish would function the same as it does now (allows SR if it duplicates an effect allowing SR, doesn't otherwise). Regarding the extra check, do you mean determining if a spell allows SR? Hopefully, there shouldn't be a noticeable delay for that, since determining whether a spell either (A) has a target/is a ray or (B) is an instantaneous AoE that affects people shouldn't take long at all, or at least no longer than checking whether it says SR: Yes in the book.

I'll be seeing the DM this afternoon and showing him this thread; thanks for everyone's help thus far. Fectin, if you wanted to speed up SR in-game and try to standardize it/eliminate things like the should-be-Evocation orbs, how would you go about it?
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