Illumina

Magical Item, greatsword, requires attunement by a Good-aligned creature with martial weapons proficiency, Legendary

The Illumina is a brilliant, bright beacon of hope that sheds bright light in a 60-foot radius. It is an elegant, opaque, slightly purplish crystalline greatsword with a +4 bonus to attack and damage rolls.

In order to attune to the sword, your character must be Good-aligned and make a truthful vow to find and destroy its’ brother, the Darkheart, at all costs. If your character meets one or neither of these requirements, the sword will remain where it is found and refuse to let itself be wielded by you.

Properties. If you are attuned to the Illumina, you gain the following benefits:

Your Charisma ability score increases by 4, to a maximum of 30.
Weapon attacks made with the Illumina deal Force damage instead of piercing or slashing, and it ignores resistances or immunities to Force damage.
While you are holding the sword, you cannot be Charmed or Frightened, and you can innately sense any creature’s alignment. Additionally, your base walking speed doubles if you are moving towards any Evil-aligned creature you or the sword are aware of.
Evil-aligned creatures take an additional 1d6 Force damage from weapon attacks made with the Illumina.
While you are holding the Illumina, you cannot be disarmed of it for any reason. Additionally, at the start of each of your turns during combat, you gain 1d10 hit points as long as you have at least 1 hit point.
The Illumina contains 50 charges, and it gains 4d6+2 charges each day at dawn. While you are holding the sword, you can cast the following spells, requiring no material components: Command (1 charge, +1 charge for each level beyond 1^st), Misty Step (2 charges), Haste (3 charges), Revivify (3 charges), Freedom of Movement (4 charges), Hold Monster (5 charges, +1 charge for each level beyond 5^th), True Seeing (6 charges), Wind Walk (6 charges), Crown of Stars (7 charges), Divine Word (7 charges), Sequester (7 charges), Blade of Disaster (9 charges), Power Word: Heal (9 charges), and Prismatic Wall (9 charges). If you cast any of the above spells that require concentration, the Illumina concentrates on it so you don’t have to. All of the spells use your spell save DC and spell attack bonus. If your character doesn’t normally have spells, your spell save DC becomes 20, and your spell attack modifier +10.
Additionally, the following spells can be cast without expending charges: Identify, Sanctuary, See Invisibility, and Daylight.
If you are reduced to 0 hit points while wielding the Illumina, you instantly revive with 2d6+6 hit points. This trait can only activate once per long rest.

Disintegrate Armor. Once per short rest, you can use an action to make the Illumina swell with glowing, luminescent power. Any hostile creature within 30 feet of you has to succeed on a DC 18 Wisdom saving throw or become Blinded for 1 minute. An affected creature can repeat this saving throw at the end of each of their turns, ending the effect on a success.

After using this feature, your next successful attack roll made with the sword reduces your target’s armor class by an amount equal to your proficiency bonus plus your Charisma modifier. Once a creature is affected by this ability, their armor class cannot be reduced by this ability any further.

Ending Attunement. If your alignment becomes anything other than Good, the Illumina breaks its’ attunement with you and disappears in a flash of hazy, white light. The sword will warn you if it feels you are turning to the dark side.

Sentience. The Illumina is a sentient Lawful Good weapon with an Intelligence of 16, Wisdom of 25, and Charisma of 20. It has hearing and Darkvision out to 120 feet. It is proficient in Insight (+13). It has a beautiful, feminine aria of a voice that flows smoothly, melodically, and telepathically into the minds of you and your allies.

Personality. The Illumina abhors all evil acts. It values teamwork, honesty, acts of compassion, and dignity. It especially loves being used to slay demons, devils, and all manner of fiends. It does not know who or what created it, but it does know the origins of the Darkheart.