The Demise of Nessus

Round 01:The casters arm fills with a black liquid pulsing within their veins. Filling their arm from the tip of the fingers to half its length, inscribed in runes and symbols of infernal script. An orb of black darkness then begins to form within the grasp of the casters leading hand.

Round 02: The orb stops growing the caster can fire it at any intended target within 30ft.

And can now re-cast as a bonus action on any subsequent turn. It is concentration, so no other concentration spells can be cast while active.

The creature must make a constitution spell save against the casters Spell Save. On a success, the target takes 3d10+spell modifier necrotic damage. On a fail it takes half damage.

If the black orb hits the intended target, it then covers the wound in a black puss, that seeps into their skin, and tattoo's them permenantly with Infernal symbols that cannot be removed without clerical interference.

If the creature dies, its body is consumed by the black ink, and pustules form all over, as they dissolve into a black boiling puddle upon the floor, that dissapates into the earth/stone. A soul will emerge chained by black heavy manacles, and is a Specter under the control of the caster for 8hrs or death.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d10 for each slot level above 3rd.