BlivetWidget
Explorer
Inspired by the the original post on medicine checks, I decided it might be useful to go through the published material and put together a short list of the things arcana checks are being used for.
This was not as simple as I thought. Arcana is sort of a catch-all skill for anything 'weird' that doesn't fit into another category. The effects are often very specific, making it difficult to summarize the list. A medicine check can let you stabilize a dying creature. An arcana check can let you study a destroyed construct's components to determine how to create one yourself (this kind of specificity also makes the descriptions a lot wordier).
I think someone who just reads the PHB's description of the arcana skill is missing a lot of interesting things that WotC intends it to be used for. They use arcana for identify / detect magic / knock (there is still value in the spells of course, because they guarantee success), finding/disabling magic traps (this is briefly covered in the DMG), determining how to use unusual magic devices/symbols, and figuring out how to use/control constructs and machinery.
I counted 217 arcana checks across all the published 5e adventures I could look through. A DC of 0 means that no roll is required, simply proficiency. Some of these entries can be easily combined (there is a lot of trap checking / disabling), but others are rather specific and I will have to really think about how to simplify them to avoid losing too much information.
Update: I've spent some time consolidating the list down to 37 items. I believe this short list loses only a little bit of fidelity compared to the above list, though obviously a few hyperspecific details had to be dropped. If anyone feels like the list could be further consolidated, feel free to let me know. I chose not to consolidate the first 8 items because they are rules as written, while the remaining represent how WotC believes those rules should be implemented (by doing so themselves in their adventures).
This was not as simple as I thought. Arcana is sort of a catch-all skill for anything 'weird' that doesn't fit into another category. The effects are often very specific, making it difficult to summarize the list. A medicine check can let you stabilize a dying creature. An arcana check can let you study a destroyed construct's components to determine how to create one yourself (this kind of specificity also makes the descriptions a lot wordier).
I think someone who just reads the PHB's description of the arcana skill is missing a lot of interesting things that WotC intends it to be used for. They use arcana for identify / detect magic / knock (there is still value in the spells of course, because they guarantee success), finding/disabling magic traps (this is briefly covered in the DMG), determining how to use unusual magic devices/symbols, and figuring out how to use/control constructs and machinery.
I counted 217 arcana checks across all the published 5e adventures I could look through. A DC of 0 means that no roll is required, simply proficiency. Some of these entries can be easily combined (there is a lot of trap checking / disabling), but others are rather specific and I will have to really think about how to simplify them to avoid losing too much information.
Activity | DC | Source |
Recall lore about spells, magic items, eldritch symbols, magical traditions, the planes of existence, and the inhabitants of those planes. | varies | PHB |
Detect or disarm a magic trap | varies (trap DC) | DMG |
Copy a spell scroll | 10 + spell level | DMG |
Identify a spell (advantage if on your class spell list) | 15 + spell level (adv. if on class spell list) | XGE |
Craft a magic item | 0 | XGE |
Scribe a spell scroll | 0 | XGE |
Discover the presence of inconspicuous spells | varies | Sage Advice Compendium |
Contested roll: determine which of two equal spells wins (e.g. two mage hands) | 0 | Live games run by Chris Perkins |
Identify a spell from glimpsing its effects on a creature | 19 | BGDiA |
Determine the function of magic symbols | 0 | BGDiA |
Determine how to activate an unfamiliar/unusual magic item | 10 | BGDiA |
Recognize a curse and how to end it | 15 | BGDiA |
With study, recognize a curse and how to end it | 0 | BGDiA |
Determine the cause of a magic vehicle's malfunction | 15 | BGDiA |
Identify the schools of magic associated with symbols | 15 | BGDiA |
Recall lore about a fiendish structure | 25 | BGDiA |
Determine the function of unusual/unfamiliar magic items | 14 | BGDiA |
Determine how to break a curse | 12 | BGDiA |
Study a broken machine for 1 hour to determine its purpose | 20 | BGDiA |
Identify a magical effect from observing a creature | 15 | BGDiA |
Study a broken machine for 1 hour to determine its purpose | 20 | BGDiA |
Determine the function of unusual/unfamiliar magic items | 10 | BGDiA |
Determine the function of unusual/unfamiliar magic items | 20 | BGDiA |
Determine how to operate a construct | 17 | BGDiA |
Identify a spell from its effects on a creature | 18 | CoS |
Identify the general intent of a spell from overhearing part of it | 14 | CoS |
Determine a teleportation circle is flawed and dangerous | 15 | CoS |
Study bookshelves of rituals for 1 hour to determine if they are genuine | 12 | CoS |
Decipher a magic inscription in a language you understand | 15 | EKDC |
Decipher a magic inscription in a language you do not understand | 25 | EKDC |
Recognize the nature of the connection between a construct and its controller | 10 | EKSDW |
Identify statues of a diety of magic | 15 | EKSDW |
Identify the school of magic associated with symbols | 15 | EKSDW |
Notice magical emanations from a hidden portal and recognize the type of magic | 15 | EKSDW |
Identify a disguised fiend | 20 | EKSDW |
Determine a studied item is cursed | 25 | GoS |
Study an abstruse book for 8 hours to understand its general subject | 20 | GoS |
Recall lore about an obscure ritual | 14 | GoS |
Research arcane lore (15 - days spent researching) | 10-15 | GoS |
Identify a spell from its effects on an object | 16 | GoS |
Identify an aberration | 15 | GoS |
Determine the function of magic symbols | 18 | GoS |
Recognize a draconic creature | 15 | HotDQ |
Recognize a magic item | 15 | HotDQ |
Use an unfamiliar and unusual magic item | 15 | HotDQ |
Sense the presence of a spirit controlling a structure | 15 | HotDQ |
Determine how to operate a construct | 10 | KW |
Repair a construct | 15 | KW |
Determine unique features of a fiend | 12 | LLoK |
Open a magic gate | 15 | LLoK |
Hold a knowledgeable discussion on magical matters | 0 | LLoK |
Deactivate a magic hazard | 15 | LLoK |
Complete the creation of an invention using notes | 18 | LLoK |
Activate an unfamiliar and unusual magic item | 16 | LLoK |
Open a magic gate | 15 | LLoK |
Open a hatch on an operating construct | 15 | LLoK |
Recognize an astral silver cord | 15 | LLoK |
Decipher notes for operating a legendary magic item | 13 | LLoK |
Complete the creation of an invention using notes | 18 | LLoK |
Identify the planar origins of unusual materials | 14 | LLoK |
Activate an unfamiliar and unusual magic item | 16 | LLoK |
Recognize an astral silver cord | 15 | LLoK |
Activate an unfamiliar and unusual magic item | 14 | LLoK |
Activate an unfamiliar and unusual magic item | 16 | LLoK |
Complete the creation of an invention using notes | 16 | LLoK |
Determine the purpose of an alchemical apparatus | 0 | LMoP |
Recognize a magic symbol | 10 | LMoP |
Sense the aura of a magic workshop | 0 | LMoP |
Identify the source of a magic aura | 15 | LMoP |
Study notes for an hour to discover they constitute a spellbook | 0 | OotA |
Study notes for an hour to discover they contain usable alchemical recipes | 15 | OotA |
Examine symbols to determine related dieties | 16 | OotA |
Reveal the nature of a curse and how to end it | 12 | OotA |
Study notes for 8 hours to understand the 2 rituals they describe | 0 | OotA |
Notice an object is leaking magical energy and how to activate it | 0 | OotA |
Notice that a creature is from another plane | 15 | OotA |
Recall learning details of an event that has not happened in 200 years | 20 | OotA |
Activate an unfamiliar and unusual, clockwork magic device | 15 | OotA |
Open a magically-locked door | 20 | OotA |
Study books and scrolls for 10 minutes to identify the 5 most valuable | 15 | OotA |
Determine characters are under the effect of Astral Projection | 13 | OotA |
Determine if an action is required for a ritual to succeed | 20 | OotA |
Determine that a creature was raised as undead by a unique ritual | 10 | OotW |
Determine the area and type of magic that that runes can emit | 16 | OotW |
Suppress magic traps for 1 minute | 10 | OotW |
Deactivate a magic hazard | 12 | OotW |
Sense the magic of a hidden planar gate | 18 | OotW |
Examine runes to determine related dieties, general message, and powers | 15 | OotW |
Recognize the ritual purpose of a particular sigil | 10 | OotW |
Recognize that seemingly normal damage (such as fire) was caused by magic | 15 | OotW |
Examine the results of a failed ritual to determine its purpose | 10 | OotW |
Recall the effect and duration of magical effects caused by creatures | 11 | OotW |
Disrupt an open portal | 15 | OotW |
Examine a body to find evidence of magical damage | 10 | OotW |
Understands the purpose and weaknesses of magic traps | 10 | OotW |
Discern the effects of activating a magic trap | 15 | OotW |
Disable magic trap | 15 | OotW |
Open magic lock | 15 | OotW |
Understand the properties of a magic item and how it was created/modified | 10 | OotW |
Disrupt a magic item | 15 | OotW |
Reveal, with a few minutes of study, a magic item's properties | 0 | OotW |
Determine command phrase for magic item | 12 | OotW |
Determine creature is becoming undead | 15 | OotW |
Determine how long until a creature becomes undead | 20 | OotW |
Stop a creature from becoming undead | 15 | OotW |
Determine how to open a puzzle door | 10 | OotW |
Disable a magic hazard | 15 | OotW |
Study a destroyed construct's components to determine how to create one yourself | 0 | OotW |
Determine a door is magically trapped | 14 | OotW |
Disarm magical trap | 13 | OotW |
Determine how to alter a portal to confuse pursuers | 14 | OotW |
Alter a portal to confuse pursuers | 12 | OotW |
Determine how a portal system works | 0 | OotW |
Identify a magic plane/dimension | 12 | OotW |
Convincingly fake a ritual | 11 | OotW |
Determine the source of a curse | 12 | OotW |
Detect a magic trap | 16 | OotW |
Disarm a magic trap | 14 | OotW |
Determine a creature has been magically tainted, and which part of them is corrupted | 12 | OotW |
Open a magically-locked door | 15 | OotW |
Identify a magic plane/dimension | 12 | OotW |
Disable a magic trap | 15 | OotW |
Determine how to stop an ongoing ritual | 0 | OotW |
Gain control of part of an ongoing ritual | 15 | OotW |
Incorporate/remove a component of an ongoing ritual | 12 | OotW |
Begin or end an ongoing ritual effect | 12 | OotW |
End an ongoing ritual | 15 | OotW |
Notice that a landscape was shaped by magic | 15 | PotA |
Study a workshop to determine the types of magic it was used for | 0 | PotA |
Recognize the purpose and functional state of ritual circles | 15 | PotA |
Recognize a creature | 12 | RoT |
Determine the spell used by a creature's innate spellcasting | 15 | RoT |
Determine the purpose of a complex apparatus after studying for a day | 20 | RoT |
Recognize dried up ink as a type used for magical writing | 0 | RoT |
Discover a thin line of magical salt | 12 | RoT |
Determine an object is part of a construct | 15 | SKT |
Determine an object has magic properties | 15 | SKT |
Determine that symbols are magical | 0 | SKT |
Determine how long a portal will remain open | 17 | SKT |
Identify a wondrous artifact | 18 | SKT |
Determine how to break a psychic link | 15 | TftYP |
Determine the school of magic associated with symbols | 0 | TftYP |
Determine the nature of a magic gate | 10 | TftYP |
Disrupt a magic gate once its nature is understood | 15 | TftYP |
Use an unfamiliar and unusual magic item | 15 | TftYP |
Determine that magic runes are gibberish | 0 | TftYP |
Identify the magic effect of symbols | 15 | TftYP |
Suppress a magic trap | 15 | TftYP |
Determine the magic effect of runes | 15 | TftYP |
Suppress the magic effect of runes (requires 3 consecutive successes) | 15 | TftYP |
Determine the nature of a rift | 10 | TftYP |
Determine a rift is dangerous | 15 | TftYP |
Determine how to distrupt a circle's magic for 1 minute | 10 | TftYP |
Perform unfamiliar and unusual ritual | 15 | TftYP |
Determine the effect of magic runes | 15 | TftYP |
Destroy magic runes | 20 | TftYP |
Determine the details of a ritual from inspecting its components | 20 | TftYP |
Activate a magic circle and learn the details of its effects | 20 | TftYP |
Discern the value of ritual ingredients | 15 | TftYP |
Discern the value of ritual ingredients | 15 | TftYP |
Discern how to use magic symbols | 10 | TftYP |
Suppress the magic effect of symbols for 1 minute | 10 | TftYP |
Suppress the magic effect of symbols for 2 minutes | 15 | TftYP |
Activate a magic gate | 20 | TftYP |
Activate a golem | 15 | TftYP |
Discern the value of ritual ingredients | 15 | TftYP |
Discern the value of ritual ingredients | 15 | TftYP |
Discern how a magic item works and how to disable it | 15 | TftYP |
Discern how to disable a magic item | 10 | TftYP |
Disable a magic item (requires 3 consecutive successes) | 15 | TftYP |
Determine that a magic item is failing | 13 | TftYP |
Determine the nature of a secret magic trap | 20 | TftYP |
Recognize teleportation circle and memorize its sigils | 0 | ToA |
Identify a construct | 10 | ToA |
Use a teleporter intended to only allow another creature's use | 20 | ToA |
Identify a fiend | 15 | ToA |
Recall lore about planar vortices | 10 | ToA |
Recall lore about a magic item | 15 | ToA |
Determine a magic item's purpose and current use | 20 | ToA |
Determine how to destroy a magic item | 25 | ToA |
Identify a phylactery | 15 | ToA |
Determine how to end a magic effect | 17 | ToA |
Reconstruct a summoning circle | 15 | WDDotMM |
Determine that magic is being faked | 10 | WDDotMM |
Identify a spell from the damage it caused | 19 | WDDotMM |
Identify a magic item | 15 | WDDotMM |
Identify an aberration | 15 | WDDotMM |
Determine how to use a magic item | 15 | WDDotMM |
Determine the purpose of magic symbols | 20 | WDDotMM |
Determine the properties and effects of a magic circle | 20 | WDDotMM |
Determine the properties and effects of a magic circle | 20 | WDDotMM |
Determine the purpose of magic symbols | 20 | WDDotMM |
Determine the properties and effects of a magic circle | 20 | WDDotMM |
Recognize the school of magic represented by magic symbols | 15 | WDDotMM |
Determine the purpose of an unusual artifact | 30 | WDDotMM |
Identify spells being researched from incomplete notes | 16 | WDDotMM |
Identify an aberration from its skull | 15 | WDDotMM |
Identify the purpose of an unfamiliar and unusual magic item and how to use it | 14 | WDDotMM |
Identify a plane | 20 | WDDotMM |
Identify a spell from the damage it caused | 16 | WDDotMM |
Determine the properties and effects of a magic circle | 13 | WDDotMM |
Identify a phylactery | 15 | WDDotMM |
Determine the function of magic symbols | 15 | WDDotMM |
Attune to a particular legendary magic item | 0 | WDDotMM |
Determine the properties and effects of a magic portal | 20 | WDDotMM |
Determine the function of magic symbols | 18 | WDDotMM |
Determine the function of magic symbols | 20 | WDDotMM |
Identify the details of a creature transformed by True Polymorph | 19 | WDDotMM |
Recognize the school of magic represented by magic symbols | 10 | WDDotMM |
Recognize the school of magic represented by magic symbols | 10 | WDDotMM |
Recognize the school of magic represented by magic symbols | 10 | WDDotMM |
Repair a damaged construct | 0 | WDDotMM |
Identify a spell from the sound of its effect | 13 | WDH |
Determine the function of a magic item | 10 | WDH |
Determine the magic effect of symbols and how to end it | 15 | WDH |
Determine the magic effect of symbols and how to end it | 15 | WDH |
Determine the school of magic associated with symbols | 15 | WDH |
Update: I've spent some time consolidating the list down to 37 items. I believe this short list loses only a little bit of fidelity compared to the above list, though obviously a few hyperspecific details had to be dropped. If anyone feels like the list could be further consolidated, feel free to let me know. I chose not to consolidate the first 8 items because they are rules as written, while the remaining represent how WotC believes those rules should be implemented (by doing so themselves in their adventures).
Items with a * require proficiency in Arcana and tend not to be used as skill checks
Recall lore about spells, magic items, eldritch symbols, magical traditions, the planes of existence, and the inhabitants of those planes |
Detect or disarm a magic trap |
Copy a spell scroll |
Scribe a spell scroll* |
Craft a magic item* |
Advantage using (and learn more from) Alchemist's Supplies, Calligrapher's Supplies, Herbalism Kit, and other tools* |
Identify a spell or magic effect during casting (advantage if on your class spell list) |
Discover inconspicuous evidence of magic use, such as spell effects/damage on a creature/object/landscape |
Examine the results of a failed ritual to determine its purpose |
Hold a knowledgeable discussion on magical matters* |
Compete to determine which of two equal spells succeeds (e.g. mage hands) |
Detect, suppress, disable, or understand the effects of a magic hazard/curse/corruption/circle/portal/lock |
Identify and recall features/ magic effects / places/ planes / items / body parts related to aberrations, constructs, fiends, necromantic undead, or extraplanar creatures |
Determine a magic item's properties* |
Determine a magic item's command phrase / how to activate it |
Determine the purpose of an alchemical or mechanical apparatus* |
Use, disable, or determine the purpose of an unusual magic item, apparatus, or mechanical device |
Use a magic item intended to prevent you from using it |
Study a magic workshop to determine its purpose* |
Sense the aura of a nearby magic item/area/portal and know the type of magic* |
Locate a magic item/area/portal from its aura |
Sense the presence of a spirit inhabiting a structure or object |
Determine how to control/disrupt/repair a construct or machine by examining it or its pieces |
Study a destroyed construct's components to determine how to create one* |
Build an invention using someone else's notes |
Determine the function/validity/school/deities/message represented by magic symbols* |
Determine how a portal system should be used* |
Determine where a portal leads or how long it will remain open |
Study notes to discover they contain spells or rituals* |
Study an abstruse book to understand its general subject |
Recognize a teleportation circle and memorize its sigils* |
Identify a magic plane/dimension |
Identify the planar origins of unusual materials |
Convincingly fake or recognize a fake spell/ritual |
Alter or disrupt an ongoing ritual |
Perform an unfamiliar or unusual ritual from notes |
Determine the purpose and value of magic items, ingredients, ritual components, or related incidental materials (e.g. dried spell ink) |
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