Enlighten Undead

After spending the casting time tracing magical pathways within a precious gemstone, you touch an undead creature you control, the target must have an Intelligence of 3 or less. The target gains an Intelligence of 10. The target also gains the ability to speak one language you know.

The enlightened 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 enlightened undead chooses whether to remain friendly to you, based on how you treated it while it was charmed.