Attack Bonus, Enemy AC, Grazing Hits, Improved Destruction - What is happening here?

[Fivetigers33]

This all started when I realized that my Improved Destruction (via dragontouched armor) wasn't improving my ability to land hits at all. I decided to do a series of tests involving various attack bonuses and which rolls were considered grazing hits and which weren't. I did all these tests in Death House on Legendary Normal fighting the the few mobs that spawn in the hall outside the nanny's room.

http://ddowiki.com/page/Improved_Destruction#Improved_Destruction
Effect: On Hit: Your target gains a stack of Armor Destruction. (-1 penalty to Armor Class, -1% of its Fortification. 20 second duration. Stacks up to 15 times.)


Turbulent Epee
+42 Attack bonus in inventory drop down
rolls
12 +43 = 55 hit
11 +53 = 64 grazing hit (the last attack in the animation sequence got an extra +10 to the roll, but it didn't seem to matter)
11 +43 (+15 stacks of improved destruction) = 69 grazing hit

How is 55 a hit but 64 and 69 are grazing hits? The initial roll seems to hold more weight than the attached attack bonus or debuff on the enemy.



Legendary Green Steel + Greater Heroism + Inspire Competence + Focusing Chant
+57 Attack Bonus in inventory drop down
12 +59 = 71 hit
11 +57 = 68 hit
9 + 59 = 68 grazing hit

Why is one 68 total a hit and the other a grazing hit?



Morninglord (on a different toon)
+104 Attack Bonus in inventory drop down
7 +104 = 111 hit
6 +104 = 110 grazing hit

Why is a 110 total a grazing hit on this toon but a 55 is a hit on a different toon?


I found a few articles on the wiki that could potentially explain the lack of Improved Destruction making much of a difference in hitting high AC enemies, but it doesn't explain the variance in what roll it takes to hit based on different character builds (i.e. 55 hits on 1 toon but 110 is a grazing hit for another)
http://ddowiki.com/page/How_to_Hit_Things
http://ddowiki.com/page/Armor_Class


If anyone can shed a little light on this for me, I'd appreciate it.

[Harkmar]

When DDO was young the AC check was a true D20 roll. Back then you could figure out a mob's attack and AC and you knew exactly how much of each you needed to trivialize an encounter. This was true all the way up to "end game" raid bosses. With the general power creep of the game the to hit check became a calculation.

The wiki has a table for it:
http://ddowiki.com/page/Ac

Because of the percent chance to hit you will get some 11s that hit and some 11s that grazing hit. If this change was not made some years back the devs would either stagnate on gear they could give us, decide that old content was going to get curb stomped by players, or have to go back and adjust old mobs. None of those are fun for a long term player base so a decision was made.

Player hits round to the nearest 5% but depending on the calculation it can slide high or low if it is already in the middle of the range.

[gwonbush]

Look back at the armor class link for the chart on how armor class works now.

Basically, back when MoTU came out 5 years ago, they flattened the die for to-hit dramatically since the bonuses got too big and have only gotten bigger since. If it was straight addition still, many characters would be literally unable to hit anything in high end content, and others would be unable to ever be hit. However, if you had an AC only 18 points lower than the "Never hit" AC, you would be always hit. This system breaks down for the higher numbers used in DDO, so they changed it to a percentile hit system based on your to hit-bonus (rounded to 5% so it matches with your D20).

The formulas are:
Monster's chance to hit: (Monster's Attack Bonus + 10.5) / (Target's Armor Class * 2)

Player's chance to hit: (Player's Attack Bonus + 10.5) / (Target's Armor Class * 2) + 20% proficiency bonus, rounded to nearest 5%

[Pilgrim1]

If thoes formulas are true it still doent explain the number the OP saw. Especially when they swiched toons.

OP: if you want to test this more you could try to see if lowering/raising you to hit bonus can change weather you hit or miss on the same number die roll.

[Tilomere]

I looked at the math. The formula are all correct.

-----------------------------

Conclusion: At 43 to hit, your % chance to hit is so low that armor destruction has little effect on your chance to hit because the increased chance to hit goes from 43% to 47%. The increase means that more 12s and some 11s will hit instead of graze.

Conclusion #2: The 3rd attack in animation does apply the +10 to hit, which is about the same as armor destruction. The increase means that more 12s and some 11s will hit instead of graze.

----------------------------

Armor penetration stacks did increase dps, as does the +10 to hit. You just don't see that with 3 cherry picked rolls. :) You don't test by cherry picking. You test by clearing a dungeon.

[OfElectricMen]

Hi!

If this change was not made some years back the devs would either stagnate on gear they could give us, decide that old content was going to get curb stomped by players, or have to go back and adjust old mobs. None of those are fun for a long term player base so a decision was made.

Sorry, but no, those weren't the only options. There were other options, and as is so often the case, they went with bad design, such as the changes being talked about.

[Vish]

I think it has to do with the die rolled
Some rolls are going to be grazing hits,
Regardless of to hit
Ha
;)

[CSQ]

This seems strange to me; I don't have any issues with hitting in heroic (I'll occasionally graze at a 2/3 on the die in heroic on a fresh toon running elite, but not once I get geared up and at level) and I don't remember having any significant issues in epic either pre-RL. If the outcomes of hits are tied to the rolls and not the attack bonuses, it seems like something has gone terribly wrong with design. I mean, it's kind of farcical to offer items with +X to hit when really that number is meaningless. Now, it could be that those animated armor targets work differently; I've noticed that it seems to take a lot of hits (damage from spells and other sources seems fine) relative to other enemies to kill animated armor on heroic, so maybe there is some behind the scenes thing where rolls below a certain threshold (say, a 10 or lower on the dice, with some wiggle room) miss or glance them regardless of the modifier. Have you noticed similar behavior from other enemies, or only these animated armors? They may not follow regular rules, since they are animated armor after all.

[Fivetigers33]

I looked at the math. The formula are all correct.

You just don't see that with 3 cherry picked rolls. :) You don't test by cherry picking. You test by clearing a dungeon.

So I went back through the formulas and I agree, they are correct. The only thing I saw from my calculations is that the game is rounding DOWN to the nearest 5%, whereas the wiki doesn't specify. Of course I haven't done thousands of tests to confirm this.


As for cherry picking, I wasn't specifically trying to find anomalies. I was looking for the threshold between hits and grazing hits. I spent about 40-45 minutes testing, so clearly at least the same time it would have taken to clear the dungeon. :-) And the results were constant.


Regarding the Roll taking precedence over the total of roll + attack bonus:
The game basically runs your attack bonus through the formula and determine what you need to roll (1d20) to hit. If your accuracy is calculated at 50%, then you need to roll 11 or better to hit. In some cases, like my Turbulent Epee test, adding an additional 10 to my attack roll won't push my overall accuracy past the next 5% increment. That's why the 12 +43 was a hit but the 11 +53 was only grazing.


Regarding Improved Destruction and other AC debutffs:
Based on the formula, at least in the case of my bard, lowering an enemy's AC isn't as effective as raising your own Attack Bonus. The Turbulent Epee +15 Improved Destruction stacks (-15 AC) was a grazing hit on 11, whereas the LGS + buffs which was exactly 15 higher Attack Bonus was a hit on a roll of 11. The formula confirms this. It seems like the higher an enemy's AC to begin with, the less effective AC debuffs will be (ironically this is when you need them the most!).


Conclusion:
While all the crazy numbers and variances are confusing at first, the devs have managed to create a formula that takes all these wildly bloated Attack Bonuses and Armor Classes and mash them down to pretty **** close to what they should be in the pen and paper version of D&D.


Coda:
I'm still disappointed that Improved Destruction doesn't really increase my accuracy!

[Mindos]

I'm still disappointed that Improved Destruction doesn't really increase my accuracy!

Maybe it doesn't help yours, but maybe it helps a party member a bit? Every bit helps.