Deathbane: Difference between revisions

Revision as of 21:12, 20 August 2022

Version 0.28: This article may not be up to date for the latest stable release of Crawl.

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 to undead targets.

Damage Calculation

Unlike most brands, bonus damage is not linearly distrubuted. 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 normal distribution with a mean of 3/2 × dam^[3] and a standard deviation of approximately 1/2 × dam^[4].

Following the normal distrubution^[5], additional damage dealt is between +100% and +200% damage, 68% of the time, and between +50% and +250% damage 95% of the time. (Assuming it deals extra damage at all)

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

↑ art-func.h:637 (0.28.0)
↑ random.cc:327 (0.28.0)
↑ random2avg returns an int, which shifts the mean slightly downwards from this value due to the effect of integer truncation for division in C++.
↑ 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.
↑ https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule

Brands
Melee weapons	General	Antimagic • Chaos • Distortion • Draining • Electrocution • Flaming • Freezing • Heavy • Holy wrath • Pain • Protection • Reaching • Spectral • Speed • Vampiric • Venom
	Weapon type	Devious • Valour • Concussion • Sundering • Entangling • Rebuke
	Artefact	Curare • Deathbane • Dragon slaying • Reaping • Silver
Launchers		Antimagic • Chaos • Draining • Electrocution • Flaming • Freezing • Heavy • Holy wrath • Penetration • Speed
Throwing weapons		Atropa • Curare • Datura • Disjunction • Poisoned • Silver

[1] rt-func.h:637 (0.28.0)

[2] random.cc:327 (0.28.0)

[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] ttps://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule

[1]

[2]

[3]

[4]

[5]

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-{{version023}}
+{{version028}}
 '''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 to undead targets.
 ==Damage Calculation==
-Additional damage is calculated according to the formula:
+Unlike most brands, bonus damage is not linearly distrubuted. Additional damage is calculated according to the formula:
-  random2avg((1 + (dam * 3)), 3))<ref>{{source ref|0.23.0|art-func.h|765}}</ref>
+  random2avg((1 + (dam * 3)), 3))<ref>{{source ref|0.28.0|art-func.h|637}}</ref>
-<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>.
+<code>random2avg</code><ref>{{source ref|0.28.0|random.cc|327}}</ref> takes the average of 3 rolls, here, which means the resulting extra damage ''approximates'' a normal 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>.
-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.
+Following the normal distrubution<ref>https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule</ref>, additional damage dealt is between +100% and +200% damage, 68% of the time, and between +50% and +250% damage 95% of the time. (Assuming it deals extra damage at all)
 ==History==