Guaranteed damage reduction - Revision history

Patrick2011b: bump

2026-04-20T21:40:12Z

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Hordes: /* What GDR Affects */

2026-04-20T18:49:03Z

‎What GDR Affects

Hordes at 22:06, 16 November 2025

2025-11-16T22:06:06Z

Hordes: /* Damage Reduction */ use code instead of parenthesis

2023-12-17T04:02:18Z

‎Damage Reduction: use code instead of parenthesis

Hordes: slight rw

2023-12-17T04:01:42Z

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Hordes: /* Damage Reduction */

2023-10-21T00:49:14Z

‎Damage Reduction

Ge0ff at 13:40, 12 October 2023

2023-10-12T13:40:54Z

Hordes: +history

2023-10-11T03:33:31Z

+history

Hordes: better grammar

2023-10-11T03:17:27Z

better grammar

Hordes: /* What GDR Affects */

2023-10-11T03:15:18Z

‎What GDR Affects

← Older revision		Revision as of 21:40, 20 April 2026
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	'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against regular melee and weapon attacks, your minimum AC reduction is equal to GDR% of the attack's damage, unless this would be higher than <code>1/2 * AC</code>. In essence, GDR is a form of insurance against poor AC rolls.		'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against regular melee and weapon attacks, your minimum AC reduction is equal to GDR% of the attack's damage, unless this would be higher than <code>1/2 * AC</code>. In essence, GDR is a form of insurance against poor AC rolls.

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 GDR only works against physical damage, either in melee, with [[reaching]], or with a ranged/throwing weapon.
-It does ''not'' apply against any sort of spell or ability. Therefore, GDR does not apply to a [[Conjurations]] spell that does physical damage. Neither does it apply against "physical" abilities like [[Slug Dart]] or [[Harpoon Shot]]. It also doesn't work against elemental melee damage, such as an [[ice beast]]'s additional cold damage.
+It does ''not'' apply against any sort of spell or ability, unless that ability specifically uses the weapon/melee damage formula (e.g., [[Manifold Assault]]). Therefore, GDR does not apply to a [[Conjurations]] spell that does physical damage. Neither does it apply against "physical" abilities like [[Slug Dart]] or [[Harpoon Shot]]. It also doesn't work against elemental melee damage, such as an [[ice beast]]'s additional cold damage.
 ==Calculating GDR==

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 {{version030}}
-'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against physical attacks, your minimum AC reduction is equal to GDR% of the attack's damage, unless this would be higher than <code>1/2 * AC</code>. Therefore, GDR is a form of insurance against poor AC rolls.
+'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against regular melee and weapon attacks, your minimum AC reduction is equal to GDR% of the attack's damage, unless this would be higher than <code>1/2 * AC</code>. In essence, GDR is a form of insurance against poor AC rolls.
 ==What GDR Affects==

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 ==Damage Reduction==
-GDR is '''not''' a form of damage reduction independent from AC. If you could have excellent GDR and terrible AC, it would do you little good. It is effectively a minimum AC roll, or a ''guaranteed'' AC roll. It is capped at (GDR% * damage taken) or (1/2 * AC), whichever is lower.
+GDR is '''not''' a form of damage reduction independent from AC. If you could have excellent GDR and terrible AC, it would do you little good. It is effectively a minimum AC roll, or a ''guaranteed'' AC roll. It is capped at <code>GDR% * damage taken</code> or <code>1/2 * AC</code>, whichever is lower.
 Let's say you take a 50 damage attack, but have 48% GDR. First, [[AC]] rolls. If AC roll is a 1, then GDR will raise the reduction to (50 * .48) = 24, meaning you actually lose 26 HP. But if your AC roll is 36, then GDR will not do anything, as you are above the guaranteed reduction of 24.

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 {{version030}}
-'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against physical attacks, your minimum AC reduction is equal to GDR% of the attack, unless it is higher than <code>1/2 * AC</code>. Therefore, GDR is a form of insurance against poor AC rolls.
+'''Guaranteed damage reduction (GDR)''' gives players a layer of protection in melee and ranged combat. Normally, each attack that hits you is reduced by a random amount up to your AC. Against physical attacks, your minimum AC reduction is equal to GDR% of the attack's damage, unless this would be higher than <code>1/2 * AC</code>. Therefore, GDR is a form of insurance against poor AC rolls.
 ==What GDR Affects==
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 ==Damage Reduction==
-GDR is '''not''' a form of damage reduction independent from AC. If you could have excellent GDR and terrible AC, it would do you little good. It is effectively a minimum AC roll, or a ''guaranteed'' AC roll. It is capped at your GDR% of damage taken, or 1/2 of your AC, whichever is lower.
+GDR is '''not''' a form of damage reduction independent from AC. If you could have excellent GDR and terrible AC, it would do you little good. It is effectively a minimum AC roll, or a ''guaranteed'' AC roll. It is capped at (GDR% * damage taken) or (1/2 * AC), whichever is lower.
 Let's say you take a 50 damage attack, but have 48% GDR. First, [[AC]] rolls. If AC roll is a 1, then GDR will raise the reduction to (50 * .48) = 24, meaning you actually lose 26 HP. But if your AC roll is 36, then GDR will not do anything, as you are above the guaranteed reduction of 24.

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 GDR is '''not''' a form of damage reduction independent from AC. If you could have excellent GDR and terrible AC, it would do you little good. It is effectively a minimum AC roll, or a ''guaranteed'' AC roll. It is capped at your GDR% of damage taken, or 1/2 of your AC, whichever is lower.
-Let's say you take a 50 damage attack, but have 48% GDR. First, [[AC]] rolls. If AC roll is a 1, then GDR will raise the reduction by (50 * .48) = 24, meaning you actually lose 26 HP. But if your AC roll is 36, then GDR will not do anything, as you are above the minimum.
+Let's say you take a 50 damage attack, but have 48% GDR. First, [[AC]] rolls. If AC roll is a 1, then GDR will raise the reduction to (50 * .48) = 24, meaning you actually lose 26 HP. But if your AC roll is 36, then GDR will not do anything, as you are above the guaranteed reduction of 24.
 If you took said 50 damage attack with 16 AC and 32% GDR, then the AC/2 limit applies instead: you'll always reduce damage by at least (16 / 2) = 8 over the expected (50 * .32) = 16.

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 ==History==
-*Prior to [[0.27]], GDR was more complex. Each set of body [[armour]] had a defined GDR, calculated by <code>(14*(Body Armour Base AC-2)^(1/2))%</code>, no matter what your actual AC was. Certain [[transmutation]]s also had a set GDR. [[Gargoyle]]s increased base GDR, while [[Draconian]]s (being unable to wear body armour) didn't have any. For more information, see [http://crawl.chaosforge.org/index.php?title=Guaranteed_damage_reduction&oldid=52698 this past revision].
+*Prior to [[0.27]], GDR was more complex. Each set of body [[armour]] had a defined GDR, calculated by <code>(14 * (Body Armour Base AC - 2)^(1/2))%</code>, no matter what your actual AC was. Certain [[transmutation]]s also had a set GDR. [[Gargoyle]]s increased base GDR, while [[Draconian]]s (being unable to wear body armour) didn't have any. For more information, see [http://crawl.chaosforge.org/index.php?title=Guaranteed_damage_reduction&oldid=52698 this past revision].
-*Prior to [[0.8]], GDR was equal to <code>(Body Armour Base AC) * (13+Armour)/17</code>.
+*Prior to [[0.8]], GDR was equal to <code>(Body Armour Base AC) * (13 + Armour) / 17</code>.
 *Prior to [[0.5]], GDR was higher.
 [[Category:Defence]][[Category:Game mechanics]]