The Goal of Life is Death

You utter a forbidden phrase that reveals the ultimate destiny of all living things. A spectral timepiece materializes behind you, its hands ticking with the finality of fate, marking all creatures of your choice, within a 120 ft radius you can see, for imminent demise. Each round, the clock advances, accumulating 3 charges of Memento Mori.

When the clock reaches 12 charges, or your concentration is broken, its energy erupts in a devastating Necrotic wave. All creatures marked by this spell must make a Constitution saving throw. On a failed save, a creature takes 12 + (1d12) necrotic damage pre Memento Mori charge, or half as much on a successful save. Additionally creatures that fail the saving throw suffer additional effects based on the number of charges as the time of the release, which can only be dispelled by Greater Restoration or Wish.

• 3-5 Charges: Creatures gain Disadvantage on Death saving throws and all healing is Halved until dispelled
• 6-8 Charges: Creatures without resistance or immunity to necrotic damage become Vulnerable to it, and those not immune lose their resistance until dispelled.
• 9-11 Charges: Creatures gain levels of exhaustion in increments of 3, with 11th charge giving no more than 9
• 12th Charge: all marked creatures ignore the damage and are instead killed, ignoring Death saving throws and regardless of any remaining hit points and can not be revived by anything less than a Wish spell.

 This spell can not be used again for a number of days equal to the total damage it would have done once released excluding any reductions with a minimum of 24 days