Vermithrax the Void-Walker

Ecology

Vermithrax is the eldest of the First Brood, a colossal black dragon whose physical form was shattered millennia ago during the Sundering. He now exists in a state of flux, partially anchored in the Material Plane and partially drifting through the Astral Plane and the Void. He does not need to eat or sleep, sustained entirely by ambient cosmic energy and the slow entropy of the universe. His mere presence in the physical world causes reality to thin and tear, creating localized zones of zero-gravity and magical dead-zones.

Appearance

Vermithrax is overwhelmingly massive, casting a shadow that can cover a small city. He does not appear entirely solid; his scales look like shards of midnight glass floating over a core of swirling, starry nebula. His wings are tattered, bleeding trails of black cosmic dust. His eyes are twin black holes, absorbing all light around them. When he roars, no sound is heard, only a terrifying, crushing silence that vibrates in the bones of those nearby.

Lair Actions (The Resonating Rift)

Fighting Vermithrax usually occurs where the barrier between worlds is thinnest. On initiative count 20:

• Reality Tear: Vermithrax rips a hole in space-time. A 20-foot sphere becomes a vacuum. Creatures inside must make a Strength save or be pulled into the Astral Plane for 1 round, taking cold and force damage before being spat back out prone.
• Void Strike: Three beams of concentrated anti-matter strike from the rift. The beams target three different characters, forcing a Dexterity save or taking heavy force damage and being stunned until the end of their next turn.
• Temporal Distortion: The flow of time stutters. All player characters must roll a d4. On an even roll, their speed is doubled and they gain an extra bonus action. On an odd roll, their speed is halved and they cannot take reactions.

Combat Mechanics

• The Silent Breath: His breath weapon is not acid or fire, but a cone of absolute entropy. Creatures caught in the blast take extreme necrotic and force damage, and any magical effects or buffs currently active on them are immediately dispelled.
• Phase Shift: As a legendary action, Vermithrax can shift entirely into the Astral Plane, becoming immune to all damage and effects from the Material Plane until the start of his next turn.
• Astral Claws: His physical attacks strike across dimensions, bypassing armor. His melee attacks target a creature's unarmored AC, and a hit deals additional force damage that cannot be resisted.
• Mind of the Void: Vermithrax is immune to psychic damage and all mind-altering effects. Anyone attempting to read his mind or telepathically communicate with him takes immediate psychic feedback damage.

Loot

Vermithrax's physical body dissolves upon death, but he leaves behind a Singularity Core, an item of immense cosmic power capable of permanently sealing (or opening) planar rifts. He also drops a few Void-Forged Scales, which master smiths can use to craft armor that grants resistance to force damage and the ability to cast Blink.