Bandax's Soulbound Serpent of Undeath

With a dark incantation, the caster channels their own life essence to call forth an undead Giant Constrictor Snake from the ethereal realm. The serpent materializes on an adjacent square of the caster's choosing, a mere 5 feet away.

The summoning demands a great sacrifice from the caster, draining half of their total hit points. If the caster possesses less than half of their hit points, the spell fails. 

The undead snake bears the same statistics as a standard Giant Constrictor (refer to Basic Rules, pg. 131). The caster can command the serpent with a mere thought, using a bonus action on their turn.

Should the caster perish while the snake remains above 0 hit points, a miraculous rebirth occurs. The caster emerges anew from the serpent's maw, taking the same space as the snake, with a single hit point and full consciousness. The snake then crumbles to dust, its purpose fulfilled and the spell's effect ending.

Upon rebirth, the caster's former body dissolves into nothingness, leaving no trace behind. The items they once carried are instantly teleported onto their newly resurrected form, preserving their equipment.

The summoned snake is bound to the material plane for 24 hours, after which it disintegrates into a fine dust. If the snake's hit points are reduced to 0 before that time, it likewise disintegrates, and the spell's effect ends.