Ioun Stone

Ioun Stones are a magical item native to the Dungeons & Dragons game. Derived from similar trinkets that appeared in the Dying Earth novels of Jack Vance, a sci-fantasy series that Gary Gygax absolutely loved, ioun stones are magical stones that a bearer induces to orbit around their head. In older editions, ioun stones were unique amongst "head slot" magical items in that they could stack, and a truly powerful individual could have a dozen or more of these stones orbiting them at the same time - a good thing, since the last tally of ioun stones puts them in the area of one hundred and fifty four varieties. Later editions generally tended to cut this aspect down, to avoid powergaming if nothing else.

Ioun stones come in a variety of distinctive shapes and colors, with each different combination of shape and color providing a new unique power. For the grand list of every ioun stone that existed up until 5th edition, /tg/ has got you covered:

• Amber sphere: “of Divine Knowledge”; Acts as holy symbol, grants insight into an opponent, grants bonus to Insight, Religion and Intelligence checks (4E, Adventurer’s Vault 2)
• Amber spindle: +1 resistance bonus on all saving throws, stacks up to +5 (Pathfinder, Rise of the Runelords #6: Spires of Xin-Shalast)
• Anhedral: +1 to AC, as bless spell (AD&D, Netheril: Encyclopedia Arcana)
• Any: “Singing Ioun Stone”, disguised as any other ioun stone, cursed to fill user’s mind with music and disrupt concentration (4E, Dragon Magazine #311)
• Balian’s yellow: +1 to a random ability score each day (AD&D, Encyclopedia Magica Vol. II)
• Black and white ellipsoid: Provides mind blank effect against scrying (3E, Dragon magazine #319)
• Black pyritohedron: Energy drain from creature or magic item; unique ioun stone (AD&D, Dragon magazine #174)
• Black spindle: Darkvision and see through mist (3E, Kobold Quarterly #6)
• Black star: Absorbs 62HP of fire damage (AD&D, Dragon Annual #2)
• Blood red orthorhomboid: Transmutes 10ft of minerals into energy; unique ioun stone (AD&D, Dragon magazine #174)
• Blue green spindle: Bestows airy water in a 10’ radius sphere at will (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Brass lozenge: Gain 2d4+2 HP once per day on command, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Bright silver cylinder: User and 200lbs. of possessions can go ethereal for one hour, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II), as cloak of etherealness, double duration (3E, Lords of Darkness)
• Bright white rectangle: +1 to saves vs acid (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Brilliant green bipyramidal: Infuses target with energy, dealing damage and heating metal; unique ioun stone (AD&D, Dragon magazine #174)
• Brown rhomboid: User and 200lbs. of possessions can assume gaseous form for one hour, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Brown sphere: Discerns the direction of north (3E, Kobold Quarterly #6)
• Cephaloid: Obscure alignment within 20 feet (AD&D, Netheril: Encyclopedia Arcana)
• Cerulean blue rhomboid: Bestows free action on user, as per the magical ring (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II), as cloak of etherealness (3E, Lords of Darkness)
• Clear crystal: “of Adaption”; Sustains creature without food or water, resist environmental temperatures, stop ongoing damage (4E, Manual of the Planes)
• Clear interconnected spheres: User becomes insubstantial; unique ioun stone (AD&D, Dragon magazine #174)
• Clear pink sphere: “Spirit storage”; if user is killed in combat, his spirit is transferred to the ioun stone and can be restored with a restoration spell (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Clear prism: Store 2d6 spell levels (AD&D, Encyclopedia Magica Vol. II)
• Clear sphere: Grants 5% magic resistance (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Clear spindle: Sustains creature without food or water (3E, DMG)
• Clear teardrop: Use detect undead at will (Ghostwalk Campaign Setting)
• Copper rectangle: Allows user to read magic at will (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Crimson sphere: +2 enhancement bonus to Intelligence, stacks up to +6 (Pathfinder, Rise of the Runelords #6: Spires of Xin-Shalast)
• Cube: +1 to Dexterity (AD&D, Netheril: Encyclopedia Arcana)
• Cylinder: +1 to saving throws vs acid (AD&D, Netheril: Encyclopedia Arcana)
• Dark blue rhomboid: “of True Sight”; darkvision, +6 to Perception and Insight, 1/day see invisible (4E PHB)
• Dark blue rhomboid: Alertness (as the feat) (3E, DMG)
• Dark green ellipsoid: +5 luck bonus to AC (3E, Lords of Darkness)
• Dark orange dodecahedron: Spell resistance 21 (3E, Lords of Darkness)
• Dark purple pyramid: as ring of wizardry IV (3E, Lords of Darkness)
• Dark purple triangle: as ring of wizardry III (3E, Lords of Darkness)
• Dark red cube: as medallion of thoughts (3E, Lords of Darkness)
• Decahedron: Sustain user without water (AD&D, Netheril: Encyclopedia Arcana)
• Decipton: Shed continual light on command (AD&D, Netheril: Encyclopedia Arcana)
• Deep black sphere: See in magical darkness, 30’ range (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Deep purple prism: Grants 60’ infravision or doubles existing infravision range (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Deep red sphere: +2 enhancement bonus to Dexterity (3E, DMG)
• Deep red sphere: Add +1 to Strength (AD&D, Encyclopedia Magica Vol. II)
• Dendroid: Adds one level of ability, not cumulative (AD&D, Netheril: Encyclopedia Arcana)
• Dodecahedron: +1 to Constitution (AD&D, Netheril: Encyclopedia Arcana)
• Dull gray: Provides 1 power point. then disintegrates (3E, Expanded Psionics Handbook)
• Dull orange rhomboid: as brooch of shielding (3E, Lords of Darkness)
• Dusty rose prism, Larloch’s: +5 deflection bonus to AC (3E, Lords of Darkness)
• Dusty rose prism: +1 insight bonus to AC (3E, DMG)
• Echinid: User can detect magic (AD&D, Netheril: Encyclopedia Arcana)
• Ellipsoid: +1 to saving throws vs poison gas (AD&D, Netheril: Encyclopedia Arcana)
• Emerald ellipsoid: 5 bonus hit points, multiple stones stack (Pathfinder, Rise of the Runelords #6: Spires of Xin-Shalast)
• Enneid: +1 to Charisma (AD&D, Netheril: Encyclopedia Arcana)
• Euhedral: Has the power of two ioun stones (AD&D, Netheril: Encyclopedia Arcana)
• Flaming yellow prism: “Heart of fire”, +2 caster level for fire spells, +6 bonus to Knowledge (the planes) and Knowledge (arcana), 1/day cast Quench or empower a fire spell (3E, 17 Relics)
• Flawed clear spindle: Cursed clear spindle (3E, Kobold Quarterly #6)
• Flickering white snowflake: +1 to saves vs cold (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Frosty white octahedron: Contains 1-4 wishes; unique ioun stone (AD&D, Dragon magazine #174)
• Glowing rose prism: +5 insight bonus to AC (3E, Kobold Quarterly #6)
• Gold ellipsoid: User and 200lbs. of possessions can go astral for one hour, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Golden ellpisoid: Intelligent stone, provides extra attacks (3E, Kobold Quarterly #6)
• Golden sphere: Distracts viewers from your disguise (3E, Kobold Quarterly #6)
• Green sphere: +1 to saving throws vs gas attacks (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Hectoid: +1 to Strength (AD&D, Netheril: Encyclopedia Arcana)
• Helicid: User can turn gaseous for one hour (AD&D, Netheril: Encyclopedia Arcana)
• Heptahedron: +1 to saving throws vs electricity (AD&D, Netheril: Encyclopedia Arcana)
• Heptid: Brings dying creature back to one hit point; stone turns to dust when used (AD&D, Netheril: Encyclopedia Arcana)
• Hexagonoid: Hums softly when poison is within 20 feet (AD&D, Netheril: Encyclopedia Arcana)
• Incandescent blue sphere, Larloch’s: +6 bonus to Wisdom (3E, Lords of Darkness)
• Incandescent blue sphere: +1 level to spell ability (AD&D, Encyclopedia Magica Vol. II)
• Incandescent blue sphere: +2 enhancement bonus to Wisdom (3E, DMG)
• Indigo blue trapezohedron: Emits fossilization pulse affecting living beings within 30 feet; unique ioun stone (AD&D, Dragon magazine #174)
• Ioun Eye: Grants 360 degree vision (AD&D, Dragon magazine #267)
• Ioun’s Flame: Bonus to Will and knowledge checks, shed light (4E, Adventurer’s Vault 2)
• Iridescent spindle: Sustains creature without air (3E, DMG)
• Jet black unspecified: Low-light vision, light sources reduced by half, improve critical range on one target, use stone as spying device, can’t knock opponents unconscious (4E, Open Grave)
• Lavender and green ellipsoid: Absorbs spells of 8th level or lower (3E, DMG)
• Light blue prism: User can understand all spoken languages (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Lime green prism: Ignore the effects of heat and ice (3E, Kobold Quarterly #6)
• Lozenge: +1 to saving throws vs charm spells (AD&D, Netheril: Encyclopedia Arcana)
• Marble sphere: Protects other ioun stones from damage (3E, Kobold Quarterly #6)
• Maroon star: User can only be harmed by magical weapons and spells (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Monoclinoid: Disables infravision within 20 feet (AD&D, Netheril: Encyclopedia Arcana)
• Mottled gray sphere: as ring of counterspells (3E, Lords of Darkness)
• Nephroid: Grants 5% magic resistance (AD&D, Netheril: Encyclopedia Arcana)
• Ochre spindle: Grants 360 degree vision (3E, Kobold Quarterly #6)
• Octahedron: Protects owner with continual mind blank spell (AD&D, Netheril: Encyclopedia Arcana)
• Onyx rhomboid: +2 enhancement bonus to Constitution, stacks up to +6 (Pathfinder, Rise of the Runelords #6: Spires of Xin-Shalast)
• Orange cube: Grants resistance to mind-affecting spells as if user had a Wisdom of 20 (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Orange prism: +1 caster level (3E, DMG)
• Orthorhomboid: +1 to Intelligence (AD&D, Netheril: Encyclopedia Arcana)
• Ovoid: Allows water walking for one hour per day (AD&D, Netheril: Encyclopedia Arcana)
• Pale aquamarine prism: “of Steadfastness”; fear immunity (4E, Adventurer’s Vault)
• Pale blue rhomboid: +2 enhancement bonus to Strength (3E, DMG)
• Pale green lozenge: Bestows nondetection (AD&D, Dragon Annual #2)
• Pale green prism, Larloch’s: +5 competence bonus on attack rolls, saves and checks (3E, Lords of Darkness)
• Pale green prism: +1 competence bonus on attack rolls, saves, skill checks and ability checks (3E, DMG)
• Pale lavender ellipsoid: Absorbs spells of 4th level of lower (3E, DMG)
• Pale turquoise: Double carrying capacity (3E, Kobold Quarterly #6)
• Pale white sphere: Recall three 9th-level spells, as pearl of power (3E, Lords of Darkness)
• Pale yellow prism: Glows like a sunrod (3E, Kobold Quarterly #6)
• Pearlized brown ellipsoid: as boots of speed, free action to activate (3E, Lords of Darkness)
• Pearly black spindle: Undead regenerate 1hp/hour (3E, Lords of Darkness)
• Pearly white prism: Repairs 1 point of damage per turn (AD&D, Encyclopedia Magica Vol. II)
• Pearly white spindle: Regenerate 1 point of damage per hour (3E, DMG)
• Pebble: Use invisibility to undead once per day (AD&D, Netheril: Encyclopedia Arcana)
• Peg: Provides a bonus to 10 arcs, wings or songs to spellcaster (AD&D, Netheril: Encyclopedia Arcana)
• Pentahedron: Free action once per day for one hour (AD&D, Netheril: Encyclopedia Arcana)
• Pink and green ellipsoid: Absorb spells of up to 4th level (AD&D, Encyclopedia Magica Vol. II)
• Pink and green sphere: +2 enhancement bonus to Charisma (3E, DMG)
• Pink ellipsoid: Adds +1 to Constitution (AD&D, Encyclopedia Magica Vol. II)
• Pink rhomboid: +2 enhancement bonus to Constitution (3E, DMG)
• Prism: User can see in magical darkness (AD&D, Netheril: Encyclopedia Arcana)
• Puce cube: Bestows ESP at will; user can scan surface thoughts of one person per round within range of 30’ (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Pulsing red star: +1 to saves vs fire (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Pure white octahedron: +1 bonus to Charisma vs beings of the same race (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Pyramid: Regenerate one hit point every four hours (AD&D, Netheril: Encyclopedia Arcana)
• Rainbow crystal: Provide 5 power points (3E, Expanded Psionics Handbook)
• Rainbow ellipsoid: User can levitate at will (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Rainbow spindle: User and 200lbs. of possessions can polymorph self for one hour, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Rectangle: +1 to saving throws vs poison (AD&D, Netheril: Encyclopedia Arcana)
• Red ellipsoid: “of Regeneration”; regeneration 10 while bloodied 1/day (4E, Adventurer’s Vault)
• Red sphere: Bestows protection from fire (AD&D, Dragon Annual #2)
• Rhomboid: Absorb 10 points of damage; turns to dust when used (AD&D, Netheril: Encyclopedia Arcana)
• Rich green star: as +5 stone of good luck (3E, Lords of Darkness)
• Rod: User can comprehend language as the spell (AD&D, Netheril: Encyclopedia Arcana)
• Round: Continual Read Magic (AD&D, Netheril: Encyclopedia Arcana)
• Scarlet and blue sphere, Larloch’s: +6 bonus to Intelligence (3E, Lords of Darkness)
• Scarlet and blue sphere: +2 enhancement bonus to Intelligence (3E, DMG/AD&D, Encyclopedia Magica Vol. II)
• Septahedron: Strength spell once per day for one hour (AD&D, Netheril: Encyclopedia Arcana)
• Sexahedron: User can teleport; stone turns to dust when used (AD&D, Netheril: Encyclopedia Arcana)
• Shining black spiral: as helm of teleportation (3E, Lords of Darkness)
• Silver ellipsoid: +5 to saves vs Necromancy (3E, Kobold Quarterly #6)
• Silver rod: +1 to saves vs electricity (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Silver sphere: Negates rear-attack bonuses (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Silvery mirror cube: +1 bonus to saves vs petrification gaze attacks (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Sky blue sphere: Delay elemental damage (3E, Kobold Quarterly #6)
• Slate blue prism: Bonus smite attempt, turn attempt or 2nd level divine spell (3E, Kobold Quarterly #6)
• Soft black rectangle: Protection against level-draining attacks, 2d10 charges (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Sphere: +1 to saving throws vs petrification (AD&D, Netheril: Encyclopedia Arcana)
• Spindle: Use invisibility to animals once per day (AD&D, Netheril: Encyclopedia Arcana)
• Star: Use light once per day (AD&D, Netheril: Encyclopedia Arcana)
• Stelloid: Sustain user without food (AD&D, Netheril: Encyclopedia Arcana)
• Tan ellipsoid: Identify spells and magic (3E, Kobold Quarterly #6)
• Tetrapton: +1 to saving throws vs cold (AD&D, Netheril: Encyclopedia Arcana)
• Tile: Projects antimagic shell around user; stone turns to dust when used (AD&D, Netheril: Encyclopedia Arcana)
• Tredyhedron: +1 to Wisdom (AD&D, Netheril: Encyclopedia Arcana)
• Triclinid: +1 to saving throws vs fire (AD&D, Netheril: Encyclopedia Arcana)
• Tubule: Grants infravision with a range of 60 feet (AD&D, Netheril: Encyclopedia Arcana)
• Unspecified rhomboid: “of Sustenance”; require no food, water or air, and require half normal rest (4E, Adventurer’s Vault)
• Vibrant purple prism: Stores three levels of spells, as a ring of spell storing, minor (3E, DMG)
• White and pink rhomboid: “of Perfect Language”; understand all spoken languages, +5 to Charisma-based skills (4E, Adventurer’s Vault)
• Yellow sphere: Sheds continual light on command (AD&D, Dragon magazine #174/Encyclopedia Magica Vol. II)
• Yellow spindle: +1 on saves vs petrification (AD&D, Dragon Annual #2)

Despite what you may think, there was never a specific individual called "Ioun" in the D&D mythos until Wizards of the Coast decided that it made sense to use that name as Ioun, the 4e Goddess of Knowledge, Skill and Prophecy.