i need assistance making a legendary artifact

[Donpoohbear]

im looking to make a legendary shotgun artifact for a campaign im running and i am running dry on ideas . id like it to have atleast 2 special effects. iwas thinking of something that could have been made in the name of garyx http://forgottenrealms.wikia.com/wiki/Garyx.

[demonslayerelf]

Basic Shotgun Rules(If you don't have some already):
Shotgun | 2d8 Piercing | Ammunition(Scatter Shot 20/40), heavy, reload 2-6(Depends on shotgun), two-handed
Meaning: The shooter makes an attack against every creature in a 40 foot cone, with advantage against creatures beyond 20 feet. Reloading each shell uses one attack(Not actions, just attacks) of the person firing the gun. Then ammunition, heavy, and two-handed are already in the game, so you know what to do with those.

Magical Shotty:
Mad Hellfire
Weapon(Shotgun), Legendary(Requires Attunement)
You gain a +3 magical bonus to attacks made with this weapon. In addition, even while un-attuned to this magical weapon, Mad Hellfire deals an additional 1d8 fire damage to all creatures it fires at, even if the shot misses. This fire damage ignores resistance or immunity to fire damage of all creatures who do not possess the Dragon-type.

Ashen Rebirth. Creatures killed by Mad Hellfire are turned to ash, and may not be resurrected through anything short of a True Resurrection spell. There is one caveat to this; If a tree or other plant is grown within a creature's ashes, once the plant has reached maturity, the plant will be subject to an Awaken spell, and will shape itself into the creature who died. The plant possesses all of the memories, abilities, and statistics of the dead creature, aside from racial abilities. Instead, the creature is now treated as a Plant-type creature and possesses a vulnerability to fire damage, but is otherwise the exact same as they were pre-death. For the purposes of resurrection spells, the plant is considered the creature's dead body.

Perfect Destruction. This weapon deals triple damage against objects and structures, including Constructs and nonsentient Plants. Objects destroyed by Mad Hellfire collapse into ashes even if the fire damage was not what destroyed them.

Shots from Madness. If a creature suffers damage from Mad Hellfire equal to or greater than their charisma score in a single shot, they are afflicted with one Indefinite Madness of the DM's choice. This madness will last until the creature is healed of the damage dealt by Mad Hellfire.

[Donpoohbear]

oh that sounds awesome i especially like the plant creature thing