Volthawk Communion

You evoke the power of the false, alien dragons of the Dark Arms, namely the Black Volt. The older, more refined variant of the Black Hawk, the Black Volt naturally have more violent, untapped power. The corresponding part affected forms a cloud of dark pink flames that creates the listed limb. This appendage is physical in nature and can become a more ferocious force by taking on Dragonrot to further sink into the draconic nature of this spell. The various forms you can take are as follows.

Doomblast. Sprouting from your Tongue forms a massive Doom Cannon, firing a worm-shaped blast at a target. You make a ranged spell attack against a target within sight, dealing 8d6 psychic damage on a successful hit and inflicting the Poisoned condition. While poisoned this way, the target is subjected to the effects of Purple Worm Poison. As a bonus action before using this form, the caster can receive 3 Dragonrot Charges to make the damage and condition bypass immunities and resistances.

Doomtail. Sprouting from your back, a 30 foot long tail forms outward to strike a target's vital areas. You make a melee spell attack against the creature to deal 10d10 piercing damage and inflict the Paralyzed condition to the attacked creature until the start of your next turn. As a bonus action before using this form, the caster can receive 3 Dragonrot Charges to inflict the Petrified condition instead. 

Doomwing. Your arms morph into two morbid, avian-like wings, flapping violently with gusting currents as you soar. You have a flying speed of 120 feet on this turn. When you fly within 20 feet of a creature for the first time, you can make a melee spell attack against them, dealing 2d8 piercing damage on a successful hit. On a critical hit, the target skips their next turn, recovering from an agonizing pain. As a bonus action before using this form, the caster can receive 6 Dragonrot Charges to make all attacks in this way a critical hit on attack rolls of 18-20.

Doomscales. Sprouting from your body forms a gilded, unnatural armor made of hardened scales, causing your prey to be stunned with your newfound glory. Your Base AC becomes 15 + your Casting Modifier for 1 minute, and in addition, creatures who start their turn within 20ft of you must make a Charisma Save or be Charmed by you for the duration. As a bonus action after using this form, the caster can receive 4 Dragonrot Charges to increase this duration to 1 hour.