Curse of the Rakshasa

A target you can target within range must make an Intelligence saving throw. If it fails the save, its next sleep is wracked with terrifying nightmares and does not gain any of the benefits of a long rest. After that, every time it finishes a long rest, it must make the Intelligence saving throw again. If it fails, it gains no benefit from the long rest. If it succeeds, the spell ends. The spell continues until the target makes its Intelligence saving throw, or until it dies.

A remove curse spell ends this effect.