Animative fusion

This spell creates a powerful undead servant. Choose two or more piles of bones or corpses of any small to large creatures within range. Your spell imbues the target with a foul mimicry of life, raising it as an undead creature. The targets become an undead abomination that has +10 hit points and attack damage per creature used. The base hit points are 20.

On each of your turns, you can use a bonus action to mentally command any creature you made with this spell if the creature is within 90 feet of you (if you control multiple creatures, you can command any or all of them at the same time, issuing the same command to each one). You decide what action the creature will take and where it will move during its next turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the creature only defends you. Once given an order, the creature continues to follow it until its task is complete.

The creature is under your control for 72 hours, after which it stops obeying any command you've given it. To maintain control of the creature for another 72 hours, you must sprinkle more blood from an abomination or abberation. 

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, you can infuse your creations with demon essence, giving them some power from the elected demon.