Ioun Stone

Wondrous item, rarity varies (requires Attunement)
An Ioun stone is named for the wizard who invented them. Many types of Ioun stone exist, each type a distinct combination of shape and color.
When you use an action to toss one of these stones into the air, the stone orbits your head at a distance of 1d3 feet and confers a benefit to you. Thereafter, another creature must use an action to grasp or net the stone to separate it from you, either by making a successful attack roll against AC 24 or a successful DC 24 Dexterity (Acrobatics) check. The user can use an action to seize and stow the stone, ending its effect.
A stone has AC 24, 10 hit points, and Resistance to all damage. It is considered to be an object that is being worn while it orbits your head.

Lavender Ioun Stone

Wondrous Item

Very Rare Abjuration Requires Attunement

Price:
Weight: -

While this pale lavender ellipsoid orbits your head, you can use your reaction to cancel a spell of 4th rank or lower cast by a creature you can see and targeting only you. Once the stone has canceled 20 ranks of spells, it burns out and turns dull gray, losing its magic. If you are targeted by a spell whose level is higher than the number of spell levels the stone has left, then the stone can't cancel it.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Scarlet Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Dexterity score increases by 2 while this deep red sphere orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Blue Ioun Stone

Wondrous Item

Very Rare Divination Requires Attunement

Price:
Weight: -

You can't be surprised while this dark blue rhomboid orbits your head. Wisdom (Perception) checks are made with Advantage.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Pink Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Constitution score increases by 2 while this pink rhomboid orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Lavender Ioun Stone

Wondrous Item

Legendary Abjuration Requires Attunement

Price:
Weight: -

While this marbled lavender and green ellipsoid orbits your head, you can use your reaction‌ to cancel a spell of 8th rank or lower cast by a creature‌ you can see and targeting only you.
Once the stone has canceled 50 spell points worth of spells, it burns out and turns dull gray, losing its magic. If you are targeted by a spell whose rank is higher than the number of spell points the stone has left, the stone can't cancel it.

Item Size Tiny
Item AC: 24
Damage Threshold: 4
Item HP: 10

Blue Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Wisdom score increases by 2 while this incandescent blue sphere orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Marbled Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Intelligence score increases by 2 while this marbled scarlet and blue sphere orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Striped Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Charisma score increases by 2 while this pink and green striped sphere orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Prismatic Ioun Stone

Wondrous Item

Legendary Alteration Requires Attunement

Price:
Weight: -

Your proficiency bonus increases by 1 while this multicolored prism orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 4
Item HP: 10

Rose Ioun Stone

Wondrous Item

Rare Abjuration Requires Attunement

Price:
Weight: -

You gain a +1 bonus to armor class while this dusty rose stone orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 2
Item HP: 10

Pearl Ioun Stone

Wondrous Item

Legendary Necromancy Requires Attunement

Price:
Weight: -

You regain 2 hit points at the end of each 10 minutes that this pearly white spindle orbits your head, provided that you have at least 1 hit point.

Item Size Tiny
Item AC: 24
Damage Threshold: 4
Item HP: 10

Violet Ioun Stone

Wondrous Item

Rare Enchantment Requires Attunement

Price:
Weight: -

This vibrant purple prism stores spells cast into it, holding them until you use them. The stone can store up to 3 spell points worth of spells at a time. When found, it contains 1d4-1 levels of stored spells chosen by the GM. Any creature can cast a spell of 1st through 3rd rank into the stone by touching it as the spell is cast. The spell has no effect, other than to be stored in the stone. If the stone can't hold the spell, the spell is expended without effect. The rank of the spell cast determines how much space it uses. While this stone orbits your head, you can cast any spell stored in it. The spell uses the spell save DC, spell attack bonus, and spellcasting ability score of the original caster, but is otherwise treated as if you cast the spell. The spell cast from the stone is no longer stored in it, freeing up space.

Item Size Tiny
Item AC: 24
Damage Threshold: 2
Item HP: 10

Turquoise Ioun Stone

Wondrous Item

Very Rare Transmutation Requires Attunement

Price:
Weight: -

Your Strength score increases by 2 while this turquoise rhomboid orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 3
Item HP: 10

Crystal Ioun Stone

Wondrous Item

Rare Enchantment Requires Attunement

Price:
Weight: -

You don't need to eat or drink while this crystal spindle orbits your head.

Item Size Tiny
Item AC: 24
Damage Threshold: 2
Item HP: 10