Undead Awakening

After spending the casting time burning and engraving the material components, you touch a Huge or smaller undead. The target must have either no Intelligence score or an Intelligence of 4 or less. The target gains an Intelligence of 10. The target also gains the ability to speak one language you know. The soul of the target is not returned which can be shown in many ways. The DM may choose to have the target be completely emotionless to show a  mock recreation of a soul, or the target may simply have the soul of another creature other than the target.

The awakened undead is charmed by you for 30 days or until you or your companions do anything harmful to it. When the charmed condition ends, the awakened undead chooses whether to remain friendly to you, based on how you treated it while it was charmed.