Death Untoward

You can cast this spell only on creatures with 15 hit points or fewer. Choose a creature that you can see within range. The creature must make a Charisma saving throw; on a success, the target becomes frightened of you and can attempt a Wisdom saving throw at the beginning of its turn until it succeeds. On a fail, the creature dies and on its next turn rises as an undead version of itself. If a revivify spell or remove curse spell is cast on the target before the transformation occurs then the effect of this spell is canceled. The creature falls under your control and retains all of its physical characteristics, abilities, features, and traits, but the target's health becomes half of your health plus 25. If the creature was a spellcaster they can no longer cast spells above 3rd level and only spells that you can cast (they retain the number of spell slots they had before death and spells cast by the Risen do not count towards your expended spell slots). Additionally, the creature must use your modifiers when casting a spell. (Example: a cleric transformed by this spell must use your Wisdom modifier when casting a Guiding Bolt).

As a bonus action on each of your turns, you can mentally command the creature transformed by this spell (the creature shares your initiative count but goes after you). You decide what the creature does and where it moves during its turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the creature will simply follow you. Once given an order, the creature will do as commanded until its task is complete. 

The creature is under your control for 30 days, during which it is kept in a state of suspended animation and is resistant to all damage except Radiant, which it is vulnerable to. At the end of the 30 days, the creature rapidly decomposes and dies. The only ways to reverse the effects are a Wish spell or Greater Restoration spell of equal level or higher cast before the 30 days are up. If the creature is returned to its original form, it has no recollection of the time spent under your control.