Difference between revisions of "Disruption"

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m (add 0.23 source code link; not sure the quoted figures are correct though?)
(update for 0.23, including statistical parsing of formula (s/o to IRC for setting me straight))
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'''Disruption''' is a special [[brand]] found only on the [[artefact]] [[great mace]], '''[[Undeadhunter]]'''. Each time it strikes an [[undead]] target, there is a 67% chance that it will deal up to 4× normal damage (average 2.).<ref>{{source ref|0.23.0|art-func.h|765}}</ref>
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'''Disruption''' is a special [[brand]] found only on the [[artefact]] [[great mace]], '''[[Undeadhunter]]'''. Each time it strikes an [[undead]] target and deals damage <code>dam</code>, there is a 2/3 probability for the target to be blasted with disruptive energy up to an additional 3× damage (4× damage in total). On average, you deal 1.67× damage.
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==Damage Calculation==
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Additional damage is calculated according to the formula:
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random2avg((1 + (dam * 3)), 3))<ref>{{source ref|0.23.0|art-func.h|765}}</ref>
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<code>random2avg</code><ref>{{source ref|0.23.0|random.cc|288}}</ref> takes the average of 3 rolls, here, which means the resulting extra damage ''approximates'' a Gaussian distribution with a mean of <code>3/2 × dam</code><ref><code>random2avg</code> returns an int, which shifts the mean slightly downwards from this value due to the effect of integer truncation for division in C++.</ref> and a standard deviation of approximately <code>1/2 × dam</code><ref>More exactly: <code>1/2 × sqrt[(dam × dam) + (dam / 3)]</code>. The difference between the two calculations is negligible, as the increase is between 0.08 and 0.083(3) for any <code>dam</code> above 1.</ref>.
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Following the 68–95–99.7 rule<ref>https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule</ref>, additional damage dealt is between 1× and 2× damage 68% of the time and between 0.5× and 2.5× damage 95% of the time.
  
 
==History==
 
==History==

Revision as of 22:37, 9 May 2019

Version 0.23: This article is up to date for the latest stable release of Dungeon Crawl Stone Soup.

Disruption is a special brand found only on the artefact great mace, Undeadhunter. Each time it strikes an undead target and deals damage dam, there is a 2/3 probability for the target to be blasted with disruptive energy up to an additional 3× damage (4× damage in total). On average, you deal 1.67× damage.

Damage Calculation

Additional damage is calculated according to the formula:

random2avg((1 + (dam * 3)), 3))[1]

random2avg[2] takes the average of 3 rolls, here, which means the resulting extra damage approximates a Gaussian distribution with a mean of 3/2 × dam[3] and a standard deviation of approximately 1/2 × dam[4].

Following the 68–95–99.7 rule[5], additional damage dealt is between 1× and 2× damage 68% of the time and between 0.5× and 2.5× damage 95% of the time.

History

Disruption was once a normal brand found on random melee weapons. In 0.4, it was removed and the holy wrath brand was enhanced instead. It was returned in 0.9 for this particular artefact.

References

  1. art-func.h:765 (0.23.0)
  2. random.cc:288 (0.23.0)
  3. random2avg returns an int, which shifts the mean slightly downwards from this value due to the effect of integer truncation for division in C++.
  4. More exactly: 1/2 × sqrt[(dam × dam) + (dam / 3)]. The difference between the two calculations is negligible, as the increase is between 0.08 and 0.083(3) for any dam above 1.
  5. https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule
Brands
Melee weapons AntimagicChaosDistortionDragon slayingDrainingElectrocutionFlamingFreezingHoly wrathPainProtectionReachingReapingReturningSpeedVampiricVenomVorpal
Launchers ElectrocutionEvasionFlameFrostPenetrationSpeedVenomVorpal
Throwing weapons ConfusionCurareDispersalExplodingFrenzyParalysisPenetrationPoisonedReturningSilverSleepSteel