Ascended Vezzuradh (The Black Storm)

This exquisitely crafted, one of a kind composite bow is made from the horns of a monstrous and shadowy creature. The material of the bow is an otherworldly, iridescent blue-black, and inlaid along the bow's limbs is an inscription in Abyssal which reads: "Strike true like the lightning of a storm. Unerringly. Without hesitation or faltering. The surety of my wielder's hand is the sealer of fates." The bow does not have a string, but instead has two prongs outstretched from the end of each limb. When a prospective wielder picks the bow up by it's riser, a string made of crackling magical lightning sparks between the four points.

It is said that this weapon was once wielded by The Dark Prince, Graz'zt, and was made lovingly for him by his sister Rhyxali, the Queen of Shadows. It appears that the magic which empowers the bow bears traces of both Graz'zt and Rhyxali's fiendish power. To the few who are aware of it's existence it is a powerful and doggedly sought-after artifact. 

(DM sidebar: Warlocks who wish to take a Hexblade's pact can use this weapon as the basis of the pact. While this can be granted as a level 1 weapon, the suggestion is that a player finds the weapon at 5th level. Awakening the weapon has a minimum requirement of attunement (with a suggested player level of 7~9) and Ascending the weapon has a minimum requirement of 15th character level. All other requirements are left to the DM's discretion. DMs can choose to add a minimum Charisma ability score as a prerequisite for Awakening or Ascending the weapon.) 

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Base Form:
You have a +1 bonus to attack and damage rolls made with this magical longbow, which does magical piercing damage and an additional 1d8 lightning damage after all other bonuses.  

Awakened Form: (Vezzuradh can only be Awakened by an Attuned wielder)
Your bonus to attack and damage rolls with this magical longbow increases to +2. The weapon's demonic nature now grants unique abilities which are activated by consuming charges. 

Charges: Vezzuradh has 12 charges. The bow gains 1 expended charge each time you deal damage to a hostile creature with a ranged weapon attack from this weapon.

Charged Shot: When you hit with this weapon you can consume 1 charge to add 1d8 Lightning damage. This effect can only be used once per turn.
Dark Words: As an action, you can consume 2 charges to cast the spell Charm Person.
Shadow Step: As a bonus action you can consume 4 charges to cast the spell Misty Step.
Graz'zt's Gift: As a bonus action you can consume 6 charges to cast the spell Lightning Arrow at 3rd level. 

Ascended Form: (Must be character level 15 or higher)
Your bonus to attack and damage rolls with this magical longbow increases to +3. Your heightened connection with Vezzuradh enhances it's previous abilities, and grants new ones. Once the weapon reaches Ascended form the player must roll on the Graz'zt Madness table. 

(All of Vezzuradh's abilities can now be up-cast. For spells, consume 2 additional charges per spell level. For Charged Shot, consume 1 additional charge per d8, to a maximum of 3.)

Charges: Vezzuradh now has 20 charges. The bow gains 2 expended charges each time you deal damage to a hostile creature with a ranged weapon attack from this weapon.

A Sister's Protection: If you are hit by a melee attack while wielding this bow you can use your reaction to consume 3 charges and gain 2d6 temporary hit points. The attacking creature takes Lightning damage equal to their damage roll, to a maximum of the number of temporary hit points you gained.
Call Shadows: As an action, you can consume 4 charges to cast the spell Darkness at 2nd level. 
Bestial Influence: As an action, you can consume 8 charges to cast the spell Charm Monster at 4th level. 
Cloak of Darkness: As an action you can consume 10 charges to cast the spell Greater Invisibility at 5th level.
Rhyxali's Rage: As an action, you can consume 12 charges to cast the spell Chain Lightning at 6th level. 

Curse of the Storm:
The Dark Prince's Mockery: If you miss an attack with this weapon while you are not attuned to it, you take 1d6 Lightning damage. If you are attuned to the weapon you only receive this penalty upon rolling a natural 1 to hit.
The Shadow Queen's Kiss: Once attuned, this weapon cannot be un-attuned from except by death or a fundamental paradigm shift from Chaotic to Lawful (thus making the wielder incompatible with the chaotic fiendish energies which power the bow). Throughout your lifetime you will be forced to contend with Rhyxali's beguiling words in moments of temptation. If you fail the DC17 Charisma saving throw, the Shadow Queen can compel you to perform a single act of her choosing. After performing the act, you are free from her temptations until 7 days have passed. 

Proficiency with a Longbow allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, willing creature with a Chaotic alignment, Damage, Combat, Ammunition, Heavy, Range, Two-Handed, Slow