Death Steal

This spell can be used on enemies or allies to 'steal' the life force from a currently dying humanoid and raise it as a zombie under the control of the caster.

When a humanoid is on zero hit points and is currently making death saving throws, this spell can be employed within 30 feet of the recipient to steal its life force and eventually raise the subject as a zombie under the control of the caster. The recipient is able to make a constitution saving throw against this effect with disadvantage if he or she wishes. On a fail, the victim is marked by the Death Steal and the latter part of this spell must be completed within a ten minute period. 

The 2nd part of this spell requires a one minute casting time and the caster must be physically touching the recipient. Upon successful completion, the body is animated with all the stats and special abilities of a zombie as found in the Player's Handbook. This zombie is under the full control of the caster, and requires a bonus action to command it. If it isn't commanded, it will merely stand in place and protect itself. If the zombie reaches zero hit points, this spell is unable to be used again on the same recipient. At this time, the subject is considered to have just died at the time the subject was initially marked for the purposes of a revivify or raise dead spell.

This spell can be renewed on a zombie before the spell expires, healing all damage taken in its undead form. If it is not renewed, the unnatural life leaves the zombie and the spell ceases to function. The spell is useful against enemies and can also be used on allies to delay the need for restorative magics. If this spell is cast on a second humanoid, the initial subject is released from the spell and loses its undead status.