Spellbook of protection - Revision history

Umbire the Phantom: /* dNetHack */ correction

2025-07-04T21:54:47Z

‎dNetHack: correction

Umbire the Phantom: /* SLASH'EM */ word choice

2025-07-04T21:44:43Z

‎SLASH'EM: word choice

Umbire the Phantom: /* GruntHack */ pasto

2025-07-04T02:25:06Z

‎GruntHack: pasto

Umbire the Phantom: /* dNetHack */ thanks chrisANG

2025-07-03T20:02:44Z

‎dNetHack: thanks chrisANG

Umbire the Phantom: hatnote, cite

2025-07-03T11:23:25Z

hatnote, cite

Umbire the Phantom: and I think this covers everything that's at least also on-wiki

2025-07-03T10:27:32Z

and I think this covers everything that's at least also on-wiki

Umbire the Phantom: premature - forgot about priests in all that somehow

2025-07-03T09:46:36Z

premature - forgot about priests in all that somehow

Umbire the Phantom: sorted out what info's pertinent to what, think I can call this up to date for vanilla - variants next

2025-07-03T04:14:08Z

sorted out what info's pertinent to what, think I can call this up to date for vanilla - variants next

Umbire the Phantom: bit of copyedit and organizing

2025-07-03T00:35:15Z

bit of copyedit and organizing

JASON10668: Add languages template.

2025-06-10T12:17:53Z

Add languages template.

@@ Line 133: / Line 133: @@
 ===dNetHack===
-In [[dNetHack]], [[notdNetHack]] and [[notnotdNetHack]], the spell of protection is the [[Noble]]'s special spell. [[Drow Healer]] women can start the game having forgotten the spell of protection.
+In [[dNetHack]], [[notdNetHack]] and [[notnotdNetHack]], the spell of protection is the [[Noble]]'s special spell. [[Drow Healer]]s of both genders can start the game having forgotten the spell of protection.
 The spell of protection functions differently than in NetHack 3.4.3, with a more "flat" AC bonus based on the hero's experience level:

@@ Line 125: / Line 125: @@
 ===SLASH'EM===
-In [[SLASH'EM]], the spell of protection is changed to a level 1 [[Spellcasting (SLASH'EM)#Protection spells|protection spell]]. [[Priest/SLASH'EM|Priests]] and [[Wizard/SLASH'EM|Wizards]] cannot start with the spellbook due to changes in their starting inventory.{{refsrc|u_init.c|1135|version=SLASH'EM 0.0.7E7F2}}{{refsrc|u_init.c|1257|version=SLASH'EM 0.0.7E7F2}} This also applies to [[SlashTHEM]].
+In [[SLASH'EM]], the spell of protection is changed to a level 1 [[Spellcasting (SLASH'EM)#Protection spells|protection spell]]. [[Priest/SLASH'EM|Priests]] and [[Wizard/SLASH'EM|Wizards]] cannot start with the spellbook due to changes in their starting inventory.{{refsrc|u_init.c|1135|version=SLASH'EM 0.0.7E7F2}}{{refsrc|u_init.c|1257|version=SLASH'EM 0.0.7E7F2}}
 ===GruntHack===

@@ Line 128: / Line 128: @@
 ===GruntHack===
-In [[GruntHack]], some monsters can use the same set of spells as the hero, including magic missile.
+In [[GruntHack]], some monsters can use the same set of spells as the hero, including the protection spell.
 ===dNetHack===

@@ Line 155: / Line 155: @@
 |}
-Casting the spell again while the hero already has protection granted from it resets the AC bonus to their current level&mdash;if the hero's unprotected AC is greater than 0 at this time, it is set to 0 before the bonus is applied. Casting the spell while it is in effect also resets the duration that it lasts for and how long the protection takes to dissipate, which is based on the hero's skill level at the time of casting:
+Casting the spell again while the hero already has protection granted from it resets the AC bonus to their current level&mdash;if the hero has protection from this spell, and their AC after all other adjustments is no better than 0, their AC is set to 0 before the bonus is applied, e.g. a Wizard with the minimum of 10 AC that casts the spell and gains 2 points of protection will have their AC be set to -2, rather than 8. Casting the spell while it is in effect also resets the duration that it lasts for and how long the protection takes to dissipate, which is based on the hero's skill level at the time of casting:
 {|class="prettytable"
@@ Line 175: / Line 175: @@
 The spell of protection can also be cast continuously via [[spell maintenance]].
 One of the [[invoke]] effects for [[the Rod of Seven Parts]] casts the protection spell and summons several high-level [[vortices]] and [[elemental]]s as temporary pets, which uses up 7 points from the [[artifact]]'s current [[enchantment]] and requires a minimum enchantment of +7.

@@ Line 8: / Line 8: @@
   |abundance=1.8%
 }}
-{{for|the property granted from this spell, [[aligned priest]]s and other sources|intrinsic protection}}
+{{for|the effect granted from this spell, [[aligned priest]]s and other sources|protection}}
 In ''[[NetHack]]'', the '''spellbook of protection''' can be [[read]] to learn the '''spell of protection'''. It is a level 1 [[clerical spell]], and the [[spellbook]] takes 5 actions to read.
 ==Generation==
-[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|88|nethack=3.6.7}}{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Priest]]s can be given a spellbook of protection as either of the two initial spellbooks in their starting inventory.{{refsrc|src/u_init.c|107|nethack=3.6.7}}{{refsrc|src/u_init.c|1020|nethack=3.6.7|name="bookstart"}} [[Wizard]]s can be given a spellbook of protection as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}<ref name="bookstart"/>
+[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|88|nethack=3.6.7}}{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Priest]]s can be given a spellbook of protection as either of the two initial spellbooks in their starting inventory.{{refsrc|src/u_init.c|107|nethack=3.6.7}}{{refsrc|src/u_init.c|1020|nethack=3.6.7|name="bookstart"}}{{refsrc|src/u_init.c|1050|nethack=3.6.7}} [[Wizard]]s can be given a spellbook of protection as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}<ref name="bookstart"/>
 Spellbooks of protection make up {{frac|9|500}} (1.8%) of all randomly-generated spellbooks. General [[store]]s, second-hand bookstores and rare books stores can stock spellbooks of protection.

@@ Line 15: / Line 15: @@
 Spellbooks of protection make up {{frac|9|500}} (1.8%) of all randomly-generated spellbooks. General [[store]]s, second-hand bookstores and rare books stores can stock spellbooks of protection.
 Writing a spellbook of protection with a [[magic marker]] uses up 5 to 9 charges.
-{{upcoming|NetHack 3.7.0|Per {{commit|319dfbdaa3e608e88e39e0a296a9c41febfc1a59}} and {{commit|495a1a9b07f0a19bddde5aecfbf43299bdaa5187}}, Wizards start each game with knowledge of the spellbook of protection's appearance.}}
+{{upcoming|NetHack 3.7.0|Per {{commit|319dfbdaa3e608e88e39e0a296a9c41febfc1a59}} and {{commit|495a1a9b07f0a19bddde5aecfbf43299bdaa5187}}, Wizards start each game with knowledge of the spellbook of protection's appearance.
 ==Description==
-When successfully [[cast]], the spell of protection grants the [[hero]] a bonus to [[AC]] dependent on their current AC, their [[experience level]] and the current level of protection granted specifically from the spell: a hero will gain up to 5 AC from the first round of protection granted by the spell, and will gain progressively less on subsequent castings depending on their current AC and protection level.{{refsrc|src/spell.c|763|nethack=3.6.7|name="cast_protection"|comment=<tt>cast_protection()</tt> function}} This protection wears off at a rate of 1 point every 10 turns, which is slowed to 1 point every 20 turns if the spell was cast at [[Expert]] skill.
+When successfully [[cast]], the spell of protection grants the [[hero]] a bonus to [[AC]] dependent on their current AC, their [[experience level]] and the current level of protection granted specifically from the spell: a hero will gain up to 5 AC from the first round of protection granted by the spell, and will gain progressively less on subsequent castings depending on their current AC and protection level.{{refsrc|src/spell.c|763|nethack=3.6.7|name="cast_protection"|comment=<tt>cast_protection()</tt> function}} This protection also raises the hero's [[magic cancellation]] to a minimum of MC1, but does not stack with magic cancellation from armor or sources of extrinsic protection such as a [[worn]] [[ring of protection]]. Protection from the spell wears off at a rate of 1 point every 10 turns, which is slowed to 1 point every 20 turns if the spell was cast at [[Expert]] skill.
 ===Details===
@@ Line 116: / Line 120: @@
 ==Variants==
 ===dNetHack===
-The protection spell functions differently in ''[[dNetHack]]''. Multiple castings of protection do not stack. When you cast the spell, it grants an AC bonus based on your [[experience level]].
+In [[dNetHack]], [[notdNetHack]] and [[notnotdNetHack]], the spell of protection is the [[Noble]]'s special spell. [[Drow Healer]] women can start the game having forgotten the spell of protection.
 {|class="prettytable"
 !Experience level
@@ Line 138: / Line 155: @@
 |}
-Casting the spell again resets your bonus to this level and refreshes the wear-off countdown. This protection wears off over time based on your casting skill at the time you cast the spell.
+Casting the spell again while the hero already has protection granted from it resets the AC bonus to their current level&mdash;if the hero's unprotected AC is greater than 0 at this time, it is set to 0 before the bonus is applied. Casting the spell while it is in effect also resets the duration that it lasts for and how long the protection takes to dissipate, which is based on the hero's skill level at the time of casting:
 {|class="prettytable"
 !Casting skill
@@ Line 155: / Line 173: @@
 |10 turns
 |}
-=== FIQHack ===
+The spell of protection can also be cast continuously via [[spell maintenance]].
-In [[FIQHack]] the protection spell only works if you are not wearing body armor.
 ==References==

@@ Line 12: / Line 12: @@
 ==Generation==
-[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Wizard]]s may be given a spellbook of protection as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}
+[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|88|nethack=3.6.7}}{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Priest]]s can be given a spellbook of protection as either of the two initial spellbooks in their starting inventory.{{refsrc|src/u_init.c|107|nethack=3.6.7}}{{refsrc|src/u_init.c|1020|nethack=3.6.7|name="bookstart"}} [[Wizard]]s can be given a spellbook of protection as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}<ref name="bookstart"/>
 Spellbooks of protection make up {{frac|9|500}} (1.8%) of all randomly-generated spellbooks. General [[store]]s, second-hand bookstores and rare books stores can stock spellbooks of protection.
@@ Line 99: / Line 99: @@
 ==Strategy==
-The protection spell is a solid utility spell that a hero can cast a few times to stack up on AC on before especially tough fights, e.g. if you are about to engage in a prolonged fight, battle a difficult or out-of-depth [[monster]], take on a group of monsters, or else are generally under-armored for a given encounter. Monks that start with the spell can benefit in particular from this to make up for their lack of [[armor]] in the early game, whether or not they plan to wear [[body armor]] later. It is also generally useful to try and bolster defenses in the midst of combat situations such as the above, though it may be more ideal to prioritize a means of [[healing]] or [[escape item]]s before trying to shore up your defenses.
+The protection spell is a solid utility spell that a hero can cast a few times to stack up on AC on before especially tough fights, e.g. if you are about to engage in a prolonged fight, battle a difficult or out-of-depth [[monster]], take on a group of monsters, or else are generally under-armored for a given encounter. It is also generally useful to try and bolster defenses in the midst of combat situations such as the above, though it may be more ideal to prioritize a means of [[healing]] or [[escape item]]s before trying to shore up your defenses.
 ==History==
-The spellbook of protection and its spell are introduced in [[NetHack 3.3.0]]. From this version to [[NetHack 3.4.3]], including some variants based on those versions, a [[bug]] is present that causes the spell to grant significantly less protection than expected, caused by the "other AC" in the formula above accidentally counting the protection spell AC twice instead of disregarding it. This is fixed in [[NetHack 3.6.0]] via {{commit|bd3244835e08813368e2caddf9fcc569dbc05c63}}.<!--In this case, the "actual" formula in practice is as follows (commenting pending whoever can get this to display properly):
+The spellbook of protection and its spell are introduced in [[NetHack 3.3.0]]. From this version to [[NetHack 3.4.3]], including some variants based on those versions, a [[bug]] is present that causes the spell to grant significantly less protection than expected, caused by the "other AC" in the formula above accidentally counting the protection spell AC twice instead of disregarding it&mdash;this bug is much more noticeable when casting the spell at high levels. This is fixed in [[NetHack 3.6.0]] via {{commit|bd3244835e08813368e2caddf9fcc569dbc05c63}}.<!--In this case, the "actual" formula in practice is as follows (commenting pending whoever can get this to display properly):
 <math>1 + \lfloor \log_2 (\text{XL}) \rfloor - \left\lfloor\frac{\text{prior spell AC}{{4-\left\lfloor\frac{\text{other AC} + 2 * \text{prior spell AC}}}{10}\right\rfloor}\right\rfloor</math>-->

@@ Line 12: / Line 12: @@
 ==Generation==
-[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Wizard]]s may be given a spellbook of magic missile as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}
+[[Monk]]s have a {{frac|3}} chance of starting with a spellbook of protection as their initial spellbook.{{refsrc|src/u_init.c|713-L715|nethack=3.6.7}} [[Wizard]]s may be given a spellbook of protection as the secondary spellbook in their starting inventory.{{refsrc|src/u_init.c|169|nethack=3.6.7}}
 Spellbooks of protection make up {{frac|9|500}} (1.8%) of all randomly-generated spellbooks. General [[store]]s, second-hand bookstores and rare books stores can stock spellbooks of protection.
@@ Line 21: / Line 21: @@
 ==Description==
-When successfully [[cast]], the spell of protection grants the [[hero]] a bonus to [[AC]] dependent on their current AC, their [[experience level]] and the current level of protection granted specifically from the spell: a hero will gain up to 5 AC from the first round of protection granted by the spell, and will gain progressively less on subsequent castings depending on their current AC and protection level. This protection wears off at a rate of 1 point every 10 turns, which is slowed to 1 point every 20 turns if the spell was cast at [[Expert]] skill.
+When successfully [[cast]], the spell of protection grants the [[hero]] a bonus to [[AC]] dependent on their current AC, their [[experience level]] and the current level of protection granted specifically from the spell: a hero will gain up to 5 AC from the first round of protection granted by the spell, and will gain progressively less on subsequent castings depending on their current AC and protection level.{{refsrc|src/spell.c|763|nethack=3.6.7|name="cast_protection"|comment=<tt>cast_protection()</tt> function}} This protection wears off at a rate of 1 point every 10 turns, which is slowed to 1 point every 20 turns if the spell was cast at [[Expert]] skill.
 ===Details===
-The exact formula for determining how much protection is granted when casting the spell uses whichever of the following two equations produce a higher result:{{refsrc|src/spell.c|763|nethack=3.6.7|comment=<tt>cast_protection()</tt> function}}
+The exact formula for determining how much protection is granted when casting the spell uses whichever of the following two equations produce a higher result:<ref name="cast_protection"/>
 :<math>1 + \lfloor \log_2 (\text{XL}) \rfloor - \text{prior spell AC}</math>
@@ Line 99: / Line 99: @@
 ==Strategy==
-The spell is an easy means of training skill in clerical spells. If you see a difficult or out-of-depth [[monster]] nearby and are willing to fight it, casting protection before engaging it is often a good idea. The spell is also useful if you are taking many hits from several monsters and/or already battling a difficult or out-of-depth monster.
+The protection spell is a solid utility spell that a hero can cast a few times to stack up on AC on before especially tough fights, e.g. if you are about to engage in a prolonged fight, battle a difficult or out-of-depth [[monster]], take on a group of monsters, or else are generally under-armored for a given encounter. Monks that start with the spell can benefit in particular from this to make up for their lack of [[armor]] in the early game, whether or not they plan to wear [[body armor]] later. It is also generally useful to try and bolster defenses in the midst of combat situations such as the above, though it may be more ideal to prioritize a means of [[healing]] or [[escape item]]s before trying to shore up your defenses.
-Monks who start with this spell may find it useful to make up for their lack of armor in the early game, and should cast it before any prolonged fight.
+==History==
 ==Messages==
-{{message|The <air> around you begins to shimmer with a golden haze.|You cast the protection spell.}}
+{{message|The <air> around you begins to shimmer with a <golden> haze.|You cast the protection spell.}}
 {{message|The <golden> haze around you becomes more dense.|You cast the spell while already protected by it.}}
 {{message|Your skin feels warm for a moment.|You cast the spell while already at the maximum amount of protection.}}
@@ Line 110: / Line 113: @@
 {{message|The <golden> haze around you disappears.|The spell has worn off completely.}}
-== Variants ==
+==Variants==
 ===dNetHack===
 The protection spell functions differently in ''[[dNetHack]]''. Multiple castings of protection do not stack. When you cast the spell, it grants an AC bonus based on your [[experience level]].
 {|class="prettytable"
@@ Line 159: / Line 161: @@
 <references/>
 {{DOD}}
-{{nethack-360}}
+{{nethack-367}}
 [[Category:Spellbooks|Protection]]

@@ Line 1: / Line 1: @@
 {{languages}}
-{{spellbook|name=protection|level=1|type=clerical|turns=3|direction=non-directional|abundance=1.83%}}
+{{spellbook
-In ''[[NetHack]]'', the '''[[spellbook]] of protection''' allows the player to learn the '''protection''' spell. The spell is unrelated to [[protection]] granted by [[priest]]s or [[pray]]ing.
+==Generation==
-==Generation==
+{{upcoming|NetHack 3.7.0|Per {{commit|319dfbdaa3e608e88e39e0a296a9c41febfc1a59}} and {{commit|495a1a9b07f0a19bddde5aecfbf43299bdaa5187}}, Wizards start each game with knowledge of the spellbook of protection's appearance.}}
-==Effects==
+==Description==
-Casting this spell decreases your [[AC]] temporarily; the exact reduction depends on your experience level, the amount of protection already gained from this spell, and your AC before casting the spell. The protection wears off at a rate of 1 point every 10 turns, or 1 point every 20 turns if the spell was cast with [[expert]] proficiency.
+When successfully [[cast]], the spell of protection grants the [[hero]] a bonus to [[AC]] dependent on their current AC, their [[experience level]] and the current level of protection granted specifically from the spell: a hero will gain up to 5 AC from the first round of protection granted by the spell, and will gain progressively less on subsequent castings depending on their current AC and protection level. This protection wears off at a rate of 1 point every 10 turns, which is slowed to 1 point every 20 turns if the spell was cast at [[Expert]] skill.
-===AC granted===
+===Details===
-The exact formula for determining the granted protection<ref>{{function|Spell.c|cast_protection}}</ref> is whichever of the following two is more:
+The exact formula for determining how much protection is granted when casting the spell uses whichever of the following two equations produce a higher result:{{refsrc|src/spell.c|763|nethack=3.6.7|comment=<tt>cast_protection()</tt> function}}
 :<math>1 + \lfloor \log_2 (\text{XL}) \rfloor - \text{prior spell AC}</math>
@@ Line 19: / Line 32: @@
 :<math>1 + \lfloor \log_2 (\text{XL}) \rfloor - \left\lfloor\frac{\text{prior spell AC}}{4-\left\lfloor\frac{\text{other AC}}{10}\right\rfloor}\right\rfloor</math>
-where "prior spell AC" is the AC already gained from castings of the protection spell; "other AC" is 10 minus your AC but for the spell, including all armor bonuses and [[divine protection]]; and log<sub>2</sub>(XL) is just the logarithm with base 2, according to the following table:
+For these equations, "prior spell AC" is the AC already gained from casting the spell, while "other AC" is 10 minus the hero's AC from every source other than the spell, including all armor bonuses and [[divine protection]], and log<sub>2</sub>(XL) is just the logarithm with base 2, according to the following table:
 {| class="wikitable"
@@ Line 35: / Line 48: @@
 |}
-Thus you will get 1-5 AC on the first casting depending solely on level, and on subsequent castings you will get progressively less depending on your AC and protection level.
+The table below shows in detail how much AC casting the protection spell will grant the hero based on their experience level, AC from other sources, and existing AC from the spell:
 {| class="wikitable"
@@ Line 84: / Line 97: @@
 | 16-30 ||       <-19  || 5  || 5  || 5  || 5  || 5  || 5  || 5  || 5  || 5
 |}
 ==Messages==
 {{message|The <air> around you begins to shimmer with a golden haze.|You cast the protection spell.}}
-{{message|The golden haze around you becomes more dense.|You cast the spell while already protected by it.}}
+{{message|The <golden> haze around you becomes more dense.|You cast the spell while already protected by it.}}
 {{message|Your skin feels warm for a moment.|You cast the spell while already at the maximum amount of protection.}}
-{{message|The golden haze around you becomes less dense.|The spell is wearing off.}}
+{{message|The <golden> haze around you becomes less dense.|The spell is wearing off.}}
-{{message|The golden haze around you disappears.|The spell has worn off completely.}}
+{{message|The <golden> haze around you disappears.|The spell has worn off completely.}}
 == Variants ==
@@ Line 146: / Line 158: @@
 ==References==
 <references/>
 {{DOD}}
 [[Category:Spellbooks|Protection]]

← Older revision		Revision as of 12:17, 10 June 2025
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		+	{{languages}}
	{{spellbook\|name=protection\|level=1\|type=clerical\|turns=3\|direction=non-directional\|abundance=1.83%}}		{{spellbook\|name=protection\|level=1\|type=clerical\|turns=3\|direction=non-directional\|abundance=1.83%}}