How does AC scale with level? [Archive] - Giant in the Playground Forums

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Ashtagon

2013-01-25, 05:27 AM

Yes, I know with PCs and anything with class levels its a matter of optimisation. But "typically", for out-of-the-box monsters, what kind of scaling is involved?

That is, should a CR 20 monster (in as much as anything can be typical) expect to have a typical AC around 30, 25, 20, or something else?

I'm thinking in terms of levels of optimisation expected by designers, not in terms of theoretical optimisation.

Another way to look at it is this. Should a fighter (or any good BAB class) typically expect level-appropriate foes to get easier, harder, or the same to hit as he progresses in level? How about medium-BAB characters and poor-BAB classes?

andromax

2013-01-25, 05:31 AM

Mid 30s AC is about on par for a core Monster at CR20. Have a browse here, creatures sorted by CR. List of creatures by CR. (http://www.iwozhere.com/SRD/monsters/ordered_by_cr.html)

The designers had to think about a lot more than just AC when designing creatures. For instance an easier to hit creature may have higher saves and more hit points to balance it, or it may not be balanced at all, and a similar CR creature is in practice much more difficult because of it's abilities.

Hitting foe's is one of the last things that a fighter needs to worry about at CR 20, yet unfortunately it's likely the only thing he can do. If he's survived that long, it's probably because he's pretty clever. Though with his BAB and weapon feats he should have one of the higher attack bonuses, from a strictly meager optimization level. Hitting an AC of 30 should be pretty routine.

Kelb_Panthera

2013-01-25, 05:37 AM

The monster manual's section on designing your own creature suggests an AC 13 points higher than the creature's CR. At CR 20 that'd be 33. Most of the creatures in the MM stick pretty close to this guidline too, only being a point or two off in the majority of cases where it doesn't hit the guidline exactly. More outliers start to show up in the later levels, but even then they're not off of the mark by more than 5 points in any instance.

Ashtagon

2013-01-25, 05:38 AM

andromax

2013-01-25, 05:45 AM

Well, assuming he's 20 levels of Fighter, and likely has a +5 weapon, weapon focus, g. weapon focus, and melee weapon mastery, with a STR of 26 we're looking at a to hit of +37 before you factor in any buffs. So that's a 5% miss chance. His second attack is very likely to hit as well.

Kelb_Panthera

2013-01-25, 05:47 AM

A 20th level fighter should only miss AC 30 on a natural 1. Even an extremely conservatively built fighter should be sporting str 20 by then and a +5 weapon, either naturally or from a GMW effect, is also extremely likely. Those and BAB 20 makes a +30 attack mod without even trying.

TypoNinja

2013-01-25, 05:49 AM

By "pretty routine", do you mean he should be hitting it 90% of the time, or 50%?

Not counting the fact that iterative attacks get less likely to hit as you go down, I'd say 90%.

All a fighter is good at is hitting things, I'd expect him to be able to connect with at the very least the first attack on all but a nat 1.

IndirectLemon

2013-01-25, 05:49 AM

Assuming your out of the box fighter 20, starting with a 16 str, getting a +6 str item, a +5 str tome and putting his leveling bonuses into str for another +5 ends up with a 32 str.

BAB 20 + 11 (str) + 5 (weapon bonus) + 3 (various weapon specialization feats)

Thats +39 without even trying really, so an attack routine of +39/+34/+29/+24 Meaning you just have to roll *not 1* 3 times followed by a 6+ to hit 4 times per round assuming AC 30.

Of course most high level fighters use powerattack for extra damage and would lower their chance to hit to do more damage... but if a fighter absolutely had to hit something he can. (assuming he doesn't roll a 1, or you houserule a 1 isn't a miss if you still hit the target because fighters need help :P)

Edit: Remember I didn't even consider items that make people flatfooted or attack touch AC etc.

Eldariel

2013-01-25, 06:59 AM

Well, CR 20 has Pit Fiend at AC 40 and Old Red Wyrm has AC 37 accounting for Mage Armor; Black Wyrm is AC 43 by the same token. I generally treat AC 40 as the average for CR 20 accounting for basic items and spell-based bonuses that generally don't appear in the monsters' stat blocks (obviously more important enemies are more impressively equipped).

Tarrasque obviously doesn't but that's not really his game anyways. Balor is probably wearing some armor so the listed AC 35 isn't the whole story.

Ashtagon

2013-01-25, 07:04 AM

So I can reasonably assume that monsters who are playing the AC game have an average of +1.5 AC per level (from a starting point of 10)?

Eldariel

2013-01-25, 07:05 AM

So I can reasonably assume that monsters who are playing the AC game have an average of +1.5 AC per level (from a starting point of 10)?

About. Can have. Can be bit higher or lower. Here's the list of SRD averages, maximums and minimums for each CR:
{table]|hp|init|AC|touch|ff_ac|bab|fort|ref|will
Summary for 'challenge_rating' = 1/10 (2 detail records)
Avg|1.00|1.50|15.50|15.50|14.00|0.00|2.00|3.50|2.0 0
Max|1|2|16|16|14|0|2|4|2
Summary for 'challenge_rating' = 1/8 (2 detail records)
Avg|1.00|2.00|14.00|14.00|12.00|0.00|2.00|3.00|0.5 0
Max|1|2|14|14|12|0|2|4|1
Summary for 'challenge_rating' = 1/6 (4 detail records)
Avg|4.50|1.75|13.75|13.25|12.00|0.25|2.50|4.00|1.0 0
Max|11|2|14|14|12|1|4|4|2
Summary for 'challenge_rating' = 1/4 (8 detail records)
Avg|3.88|1.75|14.50|13.25|12.75|0.25|2.50|2.88|0.3 8
Max|11|3|17|15|14|1|4|5|2
Summary for 'challenge_rating' = 1/3 (7 detail records)
Avg|4.43|2.57|15.71|13.14|13.71|0.14|2.29|3.14|1.1 4
Max|6|5|17|15|16|1|4|5|3
Summary for 'challenge_rating' = 1/2 (29 detail records)
Avg|6.59|1.41|14.69|11.86|13.38|0.76|2.62|2.00|0.0 3
Max|16|4|18|16|18|2|5|6|3
Summary for 'challenge_rating' = 1 (46 detail records)
Avg|12.24|1.54|15.28|11.78|13.80|1.28|3.00|2.85|0. 98
Max|31|7|23|20|18|3|6|6|5
Summary for 'challenge_rating' = 2 (51 detail records)
Avg|20.55|2.39|15.76|11.84|13.94|2.33|4.35|4.35|2. 69
Max|42|8|23|15|22|5|8|10|6
Summary for 'challenge_rating' = 3 (72 detail records)
Avg|27.26|2.68|16.14|11.51|14.64|3.30|4.58|4.18|3. 31
Max|55|9|23|18|23|6|9|9|7
Summary for 'challenge_rating' = 4 (40 detail records)
Avg|48.23|2.23|16.00|10.45|15.05|5.20|6.45|5.10|4. 60
Max|94|6|20|18|20|9|11|9|9
Summary for 'challenge_rating' = 5 (51 detail records)
Avg|56.33|3.16|17.16|10.55|15.73|6.08|7.47|5.82|4. 82
Max|95|11|25|16|25|11|12|13|10
Summary for 'challenge_rating' = 6 (26 detail records)
Avg|69.12|3.27|18.88|11.00|17.27|7.60|8.08|6.85|6. 08
Max|133|13|29|29|24|12|14|12|12
Summary for 'challenge_rating' = 7 (45 detail records)
Avg|86.98|2.91|18.07|10.38|16.44|8.38|8.67|6.98|6. 56
Max|152|13|25|17|24|13|15|19|12
Summary for 'challenge_rating' = 8 (31 detail records)
Avg|96.48|3.19|20.00|10.58|18.32|9.43|9.19|7.65|7. 45
Max|180|10|27|20|26|15|16|14|11
Summary for 'challenge_rating' = 9 (31 detail records)
Avg|130.65|3.61|21.74|10.45|19.68|11.97|12.13|9.81 |8.58
Max|230|14|29|18|28|18|19|22|13
Summary for 'challenge_rating' = 10 (19 detail records)
Avg|136.53|2.79|22.58|9.26|21.42|13.21|11.63|8.58| 9.11
Max|305|8|33|13|33|24|22|19|14
Summary for 'challenge_rating' = 11 (24 detail records)
Avg|163.83|3.96|23.71|10.92|21.38|14.25|13.75|10.6 3|10.3
Max|228|15|29|25|27|24|20|25|14
Summary for 'challenge_rating' = 12 (12 detail records)
Avg|196.33|1.58|21.75|7.17|21.42|17.00|15.42|9.33| 9.08
Max|300|5|28|13|28|30|25|12|15
Summary for 'challenge_rating' = 13 (12 detail records)
Avg|167.00|2.92|27.33|10.25|26.00|14.42|14.17|9.83 |12.4
Max|230|5|32|14|31|20|18|14|16
Summary for 'challenge_rating' = 14 (12 detail records)
Avg|180.33|4.50|27.00|11.00|25.17|16.17|15.92|11.8 3|14.0
Max|287|8|35|14|35|23|19|13|18
Summary for 'challenge_rating' = 15 (8 detail records)
Avg|224.63|3.50|29.75|8.13|29.50|18.88|15.75|10.63 |15.8
Max|312|5|34|11|33|24|19|14|20
Summary for 'challenge_rating' = 16 (11 detail records)
Avg|239.09|4.27|31.91|10.00|30.73|21.18|17.09|13.2 7|16.6
Max|378|8|42|16|42|31|23|16|23
Summary for 'challenge_rating' = 17 (7 detail records)
Avg|244.86|3.29|28.00|9.57|26.86|20.14|19.57|11.29 |16.2
Max|337|7|34|13|34|27|25|15|19
Summary for 'challenge_rating' = 18 (8 detail records)
Avg|302.25|6.00|32.75|8.50|31.25|24.25|19.50|15.63 |19.0
Max|375|20|37|14|37|30|23|24|23
Summary for 'challenge_rating' = 19 (10 detail records)
Avg|355.80|4.80|36.00|9.20|35.20|27.60|22.10|16.30 |19.7
Max|445|12|38|16|38|33|25|20|21
Summary for 'challenge_rating' = 20 (9 detail records)
Avg|409.33|6.00|36.44|9.11|34.44|29.56|24.22|18.67 |21.2
Max|858|12|40|17|39|48|38|29|23
Summary for 'challenge_rating' = 21 (13 detail records)
Avg|393.00|4.31|38.69|8.77|37.31|27.69|23.31|16.15 |20.5
Max|522|7|51|17|44|36|28|22|25
Summary for 'challenge_rating' = 22 (9 detail records)
Avg|452.33|7.44|40.22|11.56|36.33|29.56|23.00|19.6 7|23.7
Max|536|22|47|24|47|37|28|25|27
Summary for 'challenge_rating' = 23 (11 detail records)
Avg|480.09|8.27|39.91|12.45|35.27|31.00|26.00|21.8 2|24.6
Max|893|18|46|28|42|38|41|35|28
Summary for 'challenge_rating' = 24 (8 detail records)
Avg|622.25|9.25|42.38|12.88|37.75|37.50|29.50|24.2 5|27.3
Max|900|27|44|40|44|48|39|38|38
Summary for 'challenge_rating' = 25 (11 detail records)
Avg|600.27|8.55|44.18|18.36|39.82|34.09|27.55|24.0 0|28.7
Max|1105|26|52|50|50|40|45|36|41
Summary for 'challenge_rating' = 26 (7 detail records)
Avg|420.29|10.43|44.29|27.14|39.57|27.00|21.14|20. 14|26.2
Max|680|17|50|48|43|40|32|29|32
Summary for 'challenge_rating' = 27 (4 detail records)
Avg|625.25|10.00|46.75|19.25|40.25|43.50|31.75|27. 75|32.7
Max|817|20|52|32|45|75|40|37|41
Summary for 'challenge_rating' = 28 (4 detail records)
Avg|894.25|16.25|53.50|26.50|43.25|42.50|37.00|37. 00|31.5
Max|1102|25|57|47|57|60|45|44|35
Summary for 'challenge_rating' = 29 (2 detail records)
Avg|472.00|12.00|50.50|30.00|42.50|21.50|25.00|25. 50|24.5
Max|814|17|51|38|48|33|40|39|32
Summary for 'challenge_rating' = 30 (4 detail records)
Avg|1064.25|2.00|40.75|13.50|40.25|48.25|36.00|26. 25|38.7
Max|1785|6|58|26|58|70|47|37|50
Summary for 'challenge_rating' = 31 (2 detail records)
Avg|788.50|3.50|58.00|16.00|56.50|42.50|34.00|24.5 0|33.5
Max|877|4|64|20|64|45|37|25|38
Summary for 'challenge_rating' = 32 (1 detail record)
Avg|433.00|18.00|40.00|20.00|30.00|42.00|19.00|29. 00|29.0
Max|433|18|40|20|30|42|19|29|29
Summary for 'challenge_rating' = 33 (2 detail records)
Avg|605.50|-2.00|60.00|0.00|60.00|72.00|32.00|30.00|33.0
Max|608|-2|60|0|60|72|32|30|33
Summary for 'challenge_rating' = 34 (2 detail records)
Avg|1100.00|9.50|54.00|16.00|50.50|52.50|42.00|32. 50|39.5
Max|1362|15|61|19|61|62|48|42|43
Summary for 'challenge_rating' = 35 (5 detail records)
Avg|1011.80|12.60|62.00|13.80|53.20|48.40|41.60|34 .20|31.0
Max|1075|24|67|18|67|50|46|52|43
Summary for 'challenge_rating' = 36 (1 detail record)
Avg|1676.00|11.00|58.00|3.00|57.00|72.00|55.00|47. 00|39.0
Max|1676|11|58|3|57|72|55|47|39
Summary for 'challenge_rating' = 37 (1 detail record)
Avg|1292.00|4.00|74.00|20.00|74.00|55.00|46.00|29. 00|47.0
Max|1292|4|74|20|74|55|46|29|47
Summary for 'challenge_rating' = 39 (3 detail records)
Avg|1430.00|7.00|66.67|18.00|62.33|68.00|55.67|37. 67|45.0
Max|1728|13|81|22|81|96|75|55|52
Summary for 'challenge_rating' = 41 (1 detail record)
Avg|1856.00|14.00|58.00|16.00|44.00|96.00|76.00|56 .00|42.0
Max|1856|14|58|16|44|96|76|56|42
Summary for 'challenge_rating' = 42 (1 detail record)
Avg|1984.00|12.00|60.00|14.00|48.00|96.00|77.00|54 .00|42.0
Max|1984|12|60|14|48|96|77|54|42
Summary for 'challenge_rating' = 43 (2 detail records)
Avg|1516.00|4.00|79.50|21.50|79.50|59.00|50.00|31. 00|50.5
Max|1787|4|88|24|88|65|55|34|56
Summary for 'challenge_rating' = 48 (1 detail record)
Avg|1479.00|4.00|78.00|21.00|78.00|58.00|50.00|31. 00|50.0
Max|1479|4|78|21|78|58|50|31|50
Summary for 'challenge_rating' = 50 (2 detail records)
Avg|2472.50|7.00|83.50|19.00|78.50|83.00|72.00|44. 50|51.5
Max|2880|10|95|26|95|96|84|52|61
Summary for 'challenge_rating' = 52 (1 detail record)
Avg|1732.00|4.00|85.00|23.00|85.00|63.00|54.00|33. 00|54.0
Max|1732|4|85|23|85|63|54|33|54
Summary for 'challenge_rating' = 57 (2 detail records)
Avg|1517.00|7.00|81.00|26.50|81.00|60.00|49.00|33. 00|43.0
Max|2006|10|92|28|92|68|59|36|59
Summary for 'challenge_rating' = 59 (1 detail record)
Avg|2362.00|4.00|102.00|28.00|102.00|75.00|64.00|3 9.00|65.0
Max|2362|4|102|28|102|75|64|39|65
Summary for 'challenge_rating' = 61 (1 detail record)
Avg|2299.00|4.00|99.00|27.00|99.00|73.00|63.00|38. 00|63.0
Max|2299|4|99|27|99|73|63|38|63
Summary for 'challenge_rating' = 66 (1 detail record)
Avg|2613.00|4.00|106.00|29.00|106.00|78.00|68.00|4 1.00|68.0
Max|2613|4|106|29|106|78|68|41|68[/table]
Should give you some idea of the variance already within the system. Though frankly, level 20 characters are expected to be able to deal with AC 50+ enemies already so, yeah, you really don't need to hold back. There's one at CR 21 which should be kinda par de course fight for level 20 characters.

Hopeless

2013-01-25, 07:06 AM

Ashtagon

2013-01-25, 07:11 AM

I believe you're forgetting hit points so even if the fighter does hit they aren't going to cause any kind of significant damage unless they use Power Attack and the like which lowers that chance to hit accordingly.

CR 9 dragon with 199hp?

Disagree. I'm not forgetting hit points. I'm just not interested in them for the purpose of this enquiry.

Similarly, I won't suggest that you were forgetting about Will saves.

TypoNinja

2013-01-25, 07:23 AM

So I can reasonably assume that monsters who are playing the AC game have an average of +1.5 AC per level (from a starting point of 10)?

Some critters are better at it than others, for example Animals and Vermin tend to have craptastic AC's, while things like outsiders and dragons pull in mass quantities of nat armor.

According to the table above the average AC on a CR 20 encounter is 36 and a bit with a max of 40, so yea base ten plus 1.5 a level but that's for things that are invested completely in their AC.

Eldariel

2013-01-25, 07:38 AM

Some critters are better at it than others, for example Animals and Vermin tend to have craptastic AC's, while things like outsiders and dragons pull in mass quantities of nat armor.

According to the table above the average AC on a CR 20 encounter is 36 and a bit with a max of 40, so yea base ten plus 1.5 a level but that's for things that are invested completely in their AC.

There are outliers tho; for instance, at CR 16 there's an AC 42. AC 33 at CR 10 and AC 35 at CR 14. So it's far from a hard and fast rule. And that table is with e.g. Dragons not using Mage Armor and no monster wearing any of their Treasure as Armor (high CR humanoid monsters have so much treasure they'll easily add 5-10 to their AC after being equipped). The higher, the more those increases amount to.

Diovid

2013-01-25, 08:13 AM

So I used the numbers above (from a CR of 1/10 to a CR of 31) in a simple statistical analysis (linear regression for those interested) and I got the following significant results:

AC = 12.127 + (1.187 * CR)
AC = 13.999 + (.627 * CR) + (.022 * CR * CR)

With the later model being slightly better. For a CR of 20, the first model gives an AC of 35.867 and the second model gives an AC of 35.339.

Touch AC = 10.447 + .113 * CR
Touch AC = 13.186 - (.707 * CR) + (.033 * CR * CR)

For a CR of 20, the first model gives a touch AC of 12.707 and the second model gives a touch AC of 12.246 (yea, these numbers make no sense considering the data but that's what the analysis said, this has to do with the Touch AC of creatures slowly dropping when their CR increases and then suddenly climbing very fast after a CR of 21 or so).

Flat-Footed AC = 11.035 + (1.102 * CR)
Flat-Footed AC = 12.222 + (.746 * CR) + (.014 * CR * CR)

For a CR of 20, the first model gives a flat-footed AC of 33.075 and the second model gives a flat-footed AC of 32.742.

Edit: I decided to redo the above analyses but excluding the creatures with a CR above 21. The results are below.

AC = 12.743 + (1.066 * CR)
AC = 14.622 + (.368 * CR) + (.037 * CR * CR)
AC (CR = 20) = 34.063
AC (CR = 20) = 36.782

Touch AC = 11.908 - (.168 * CR)
Touch AC = 12.305 - (.316 * CR) + (.008 * CR * CR)
Touch AC (CR = 20) = 8.548
Touch AC (CR = 20) = 9.185

Flat-footed AC = 11.176 + (1.075 * CR)
Flat-footed AC = 13.116 + (.354 * CR) + (.039 * CR * CR)
Flat-footed AC (CR = 20) = 32.676
Flat-footed AC (CR = 20) = 35.796

Incorrect

2013-01-25, 08:22 AM

Dictum_Mortuum brings us this knowledge in his "The Wizard's Handbook":

http://img233.imageshack.us/img233/5527/touchnormalacro0.jpg

Source: http://community.wizards.com/go/thread/view/75882/19869222/The_Wizards_Handbook

Renchard

2013-01-25, 09:24 AM

Hmm...if you smooth out that curve, 15 + 1/lvl looks pretty reasonable.

BowStreetRunner

2013-01-25, 09:38 AM

Ravens_cry

2013-01-25, 09:49 AM

What further complicates things are DR, so you might need to power attack even if it makes you miss much more often, and miss chances, both of which become much more prevalent at higher levels.

Kornaki

2013-01-25, 11:00 AM

Just keep in mind that whatever is the average AC for a particular CR needs to be balanced with the overall design of the monster. There are lots of different defensive abilities (armor class, saving throws, damage reduction, regeneration, energy resistance, spell resistance, fast healing) and lots of different offensive abilities as well. If you were to give a single monster every defensive ability at levels that are average for the CR as well as every offensive ability at an average level for the CR, you would actually have a monster that should be a higher CR. Your monsters should have weaknesses that offset their strengths, whether it be some defensive abilities that are lower than average, a smaller total number of different defensive abilities, weaker or fewer offensive abilities, or a small thermal exhaust port that an X-Wing fighter pilot could hit without using his targeting computer.

This gives an interesting question: if a monster had all average stats for a CR 18 monster (no weaknesses, no strengths) and also had no special abilities/qualities, what would its challenge rating be?

If we're really lucky it's challenge rating 18, then you can vary the stats and give it special abilities/qualities from there. If not, maybe you just need to take the CR 20 stats to get a CR 18 monster (or CR 16 stats to get a CR 18 monster). This could lead to a formulaic way to come up with balanced monster stats

Eldariel

2013-01-25, 11:29 AM

This gives an interesting question: if a monster had all average stats for a CR 18 monster (no weaknesses, no strengths) and also had no special abilities/qualities, what would its challenge rating be?

If we're really lucky it's challenge rating 18, then you can vary the stats and give it special abilities/qualities from there. If not, maybe you just need to take the CR 20 stats to get a CR 18 monster (or CR 16 stats to get a CR 18 monster). This could lead to a formulaic way to come up with balanced monster stats

What movement modes would it have? If it can't affect people under basic low level magic (Greater Invisibility, Fly), it can't be a credible threat outside cramped environments. This is a problem e.g. The Tarrasque suffers seriously of, which is why Big T isn't really CR 20 at least as a threat to the party; killing it is harder (especially a houseruled Big T with Immunity to Ability Drain) but it has serious trouble threatening PCs.

ericgrau

2013-01-25, 12:40 PM

The guideline of AC~=13+CR is pretty consistent, though AC actually scales slightly faster than CR. Around 1.2/CR maybe. So the chance of hitting stays fairly even. I did a test a while back and it took a core fighter 2-1/2 rounds to drop a foe at level 5, and 2-1/2 rounds to drop a foe at level 15, with the first round being a single attack. It's remarkably consistent.

The touch AC table is a bit misleading because at high levels you get a lot of 4s and 6s averaged in. If you take out the auto-hits touch AC does increase a little and at any level there is some variance of course. Between that, firing into melee and other penalties I've noticed at most levels that touch AC is actually tough to hit for poor BAB. Maybe around level 10-15 it gets easier, though even at level 20 it's possible to miss foes firing into melee.

Especially at higher levels stats alone don't determine a monster's CR. Most high level foes have special abilities. At low level foes less have special abilities, but those that do are bringing down the average on the stats.

Ashtagon

2013-01-25, 01:04 PM

Based on earlier spreadsheet work by others, i did my own.

I excluded CR<1, because such creatures could never be used in one-on-one fights with PCs; their low CR means they are mob monsters by definition, which skews their usage patterns in a game. They fight by numbers, not by playing the AC game.

I also excluded CR>20, because that is outside the realms of normal play with regard to level-appropriate challenges. Anything at those levels which is supposedly level-appropriate automatically implies the notoriously broken epic level rules.

Finally, I considered the halfway point of the average and maximum AC at each CR. I didn't want to use the maximum directly, as it is, by definition, the outlier. On the other hand, the average will also by definition include creatures that aren't playing the AC game, and which therefore aren't a useful measure of what AC a fighter should be able to hit. Halfway between maximum and average seemed like a decent compromise.

The overall result, once you remove the string of numbers after the decimal point, is close enough to 15 + CR that the difference doesn't matter.

I'm mildly astonished that it comes out so neatly.

Eldariel

2013-01-25, 01:19 PM

You should go up to at least CR 24 since a level 20 party is expected to be able to reasonably take on a single CR 24 challenge.

TypoNinja

2013-01-25, 05:54 PM

There are outliers tho; for instance, at CR 16 there's an AC 42. AC 33 at CR 10 and AC 35 at CR 14. So it's far from a hard and fast rule. And that table is with e.g. Dragons not using Mage Armor and no monster wearing any of their Treasure as Armor (high CR humanoid monsters have so much treasure they'll easily add 5-10 to their AC after being equipped). The higher, the more those increases amount to.

Intelligent/Special foes are expected to have done better, but things like preparation time and precombat buffs are either encounter specific, and/or scaled to the PC's level of optimization, so are kind of outside of our ability to offer practical advice on.

Lans

2013-01-31, 06:04 PM

Looking at the srd the average AC looks to be around 39 for level 20 creatures assuming they only use at will defensive spell like abilities, and mage armor, and no other defensive items, feats or spells, which they quite frankly have access to. If a red dragon takes mage armor, shape soulmeld, and bonus essentia his AC jumps to 41, add in a ring of deflection and its a 42.

Spuddles

2013-01-31, 06:19 PM

Monster type plays a fairly big roll. Giants tend to have relatively low ac but about 1.5x hd per CR. Animals tend to have abysmal AC but around 2x hd per CR. outsiders tend to have high ac but cr = hd. This is important because a high ac opponent is expected, in general, to have fewer hp than a low ac opponent. In the end, a fighter will end up spending about an equal number of full attacks on an enemy.

I have found that players just don't have fun vs high ac high hp opponents, as it gets into a slugfest. High ac low hp tend to be glass cannon critters with all sorts of nasty tricks. High hp low ac tend to be brutes that hit for a lot of damage. Players feel good when they are landing lots of iteratives with power attack.

Eldariel

2013-01-31, 06:49 PM

TheifofZ

2013-01-31, 07:14 PM

[...]

QFT.
Also: Caster based monsters have low AC and Health compared to others.
They make up for it with spells and magic items.

Spuddles

2013-01-31, 07:15 PM

Whatever happened to your canpaign journal, Eldarial?

Eldariel

2013-01-31, 08:11 PM

Whatever happened to your canpaign journal, Eldarial?

We've got the next session played but haven't done the write-up yet; caught up with stuff. I'll prolly get it up over this weekend, though.

Ashtagon

2013-02-01, 03:13 AM

You should go up to at least CR 24 since a level 20 party is expected to be able to reasonably take on a single CR 24 challenge.

ok, I redit it counting CR 1/2 to CR 24.

The best line that fits is: 15.368 + (CR x 1.142).

For government purposes, that approximates to 15 + CR.

Lans

2013-02-01, 09:26 AM

Thats closer to 16+CR, and only if your assuming the monsters aren't using defensive options at their disposal

akahdrin

2013-02-01, 09:46 AM

A 33 AC for a CR 20 is pitiful. If you're going to make it that low, just make it a base 10 and save the dice rolling to hit. By level 20, they'll be using brilliant energy and bypassing a lot of the armor and auto hitting on it.

If you are actually worried about AC, you should make your own NPCs. You have to figure a melee class will have a 20 BAB, probably a +5 weapon by this time unless they're really struggling, add in their strength bonus, lets go with a low 22 str assuming they have a strength item giving them so far a +31 to hit. We didn't even really go into any other spells or combat maneuvers. Even if you're a rogue BAB class you're only 5 lower and will still basically auto hit with a flank bonus and your to hit bonus via dex will probably be even higher than the str one.

So yea if you're going to propose a challenge to the PCs, at least make it a challenge. Rolling dice to just auto hit and hope you don't get a 1 is a waste of everyone's time.

Remember a CR 20 is made for a group of 20s. If you're just throwing these at players like candy and they're wading through them like nothing, either you're playing the monsters like pansies, the PCs are extremely over geared for their level (this is if they're a lot lower than 20) and you need to sunder some of their stuff, or some other bad reason.

I try to make it so that combat isn't a trivial matter and that when you're fighting a CR value = to your party, that it will take your entire party to defeat it.

Ashtagon

2013-02-01, 10:17 AM

Thats closer to 16+CR, and only if your assuming the monsters aren't using defensive options at their disposal

15.368 rounds to 16? How?

A 33 AC for a CR 20 is pitiful. If you're going to make it that low, just make it a base 10 and save the dice rolling to hit. By level 20, they'll be using brilliant energy and bypassing a lot of the armor and auto hitting on it.

If you are actually worried about AC, you should make your own NPCs. You have to figure a melee class will have a 20 BAB, probably a +5 weapon by this time unless they're really struggling, add in their strength bonus, lets go with a low 22 str assuming they have a strength item giving them so far a +31 to hit. We didn't even really go into any other spells or combat maneuvers. Even if you're a rogue BAB class you're only 5 lower and will still basically auto hit with a flank bonus and your to hit bonus via dex will probably be even higher than the str one.

So yea if you're going to propose a challenge to the PCs, at least make it a challenge. Rolling dice to just auto hit and hope you don't get a 1 is a waste of everyone's time.

Remember a CR 20 is made for a group of 20s. If you're just throwing these at players like candy and they're wading through them like nothing, either you're playing the monsters like pansies, the PCs are extremely over geared for their level (this is if they're a lot lower than 20) and you need to sunder some of their stuff, or some other bad reason.

I try to make it so that combat isn't a trivial matter and that when you're fighting a CR value = to your party, that it will take your entire party to defeat it.

This all depends on level of optimisation. What I was looking for the the expected values for monsters who are playing the AC game. I'm well aware that TO makes the answer into "how high do you want?"

Lans

2013-02-01, 10:51 AM

15.368 rounds to 16? How?

If the actual formula is 15.368 + (CR x 1.142), then for a CR 1 its 16.510 which would round to 17.

This all depends on level of optimisation. What I was looking for the the expected values for monsters who are playing the AC game. I'm well aware that TO makes the answer into "how high do you want?"

At the very least you should look at a monsters at will buffs. I don't see a balor or pit fiend running around with out unholy aura up.

TuggyNE

2013-02-02, 12:34 AM

A 33 AC for a CR 20 is pitiful. If you're going to make it that low, just make it a base 10 and save the dice rolling to hit. By level 20, they'll be using brilliant energy and bypassing a lot of the armor and auto hitting on it.

If you are actually worried about AC, you should make your own NPCs. You have to figure a melee class will have a 20 BAB, probably a +5 weapon by this time unless they're really struggling, add in their strength bonus, lets go with a low 22 str assuming they have a strength item giving them so far a +31 to hit. We didn't even really go into any other spells or combat maneuvers. Even if you're a rogue BAB class you're only 5 lower and will still basically auto hit with a flank bonus and your to hit bonus via dex will probably be even higher than the str one.

None of this takes iteratives or Power Attack into account, which is fairly significant. (Of course, Shock Trooper makes Power Attack irrelevant to the question again.)

+31/+26/+21/+16 gets about 2.30 hits per round (http://anydice.com/program/1d17) on average, which is a far cry from auto-hitting on all attacks; amusingly, this power attack calculator (http://donjon.bin.sh/d20/power/) suggests you shouldn't drop any BAB at all for optimum damage.

Assuming a Dex-based attacker at 24 Dex and +15 BAB with full TWF chain and flanking on a pair of +5 light weapons, you only get about +27/+27/+22/+22/+17/+17, which comes to almost exactly 3.00 per round. In other words, hitting half the time.

Finally, Brilliant Energy is an extremely iffy weapon special; anyone who fights a lot of constructs or undead will find it actively unhelpful, and fighting a lot of non-human-shaped enemies makes it relatively useless. (It's of no use against high natural armor, (greater) mage armor, etc.)