Deep Nightmare Encasement

You touch a sleeping creature and whisper words drawn from the Realm of Nightmares.

The target must make a Wisdom saving throw against your spell save DC.

• On a successful save, nothing happens. The target does not awaken as a result of this saving throw or any effect of this spell.
• On a failed save, if the target has 80 hit points or fewer, it dies instantly.

Regardless of the outcome, the target is immune to all spells of the Nightmare Encasement series for the next 7 days.

A creature slain by this spell cannot be restored to life. Only a Wish spell can return it to life. A creature restored in this way suffers a permanent madness.