Nimue was not going to allow Merlin's dream to come true. His latest prophesy was proof of her success. His little experiment to have Muggles live in peace and harmony with wizards and witches would fail. Muggles were just too inferior to magical folk.
She gathered her ingredients about her. Merlin was about to take a very long nap. He would have moments of consciousness, but they would be more dream then reality. She did not want to inhibit his ability to prophesy, nor his ability to see all that going on in the world. She wanted him to watch his hard work come crumbling down but not be able to react to prevent the destruction.
She set the cauldron last used to burn up some Alfalfa harvested during the last full moon. She did not want Merlin to suffer physical pains, so this would limit his hunger while under her Sleeping Draught. The stars were starting to appear as she started to add ingredients. Her goal was to add the last ingredient as the full moon set with the dawn. She hoped that this would add potency to the sleeping draught and perhaps add to the dream Merlin experienced while under it's influence.
Nimue started by adding some Acacia gum to strengthen Merlin's Psychic Powers to keep him in touch with the outside world. Once the gum was sticky she stirred in some hops to start the powers of sleep running through the potion. Sopohorous beans that had been crushed under the stars in a moonless sky were added to put Merlin into a deep, deep sleep. She simmered this together for an hour before adding calendula to induce dreams to occur while he slept. Then she stirred in some Chamomile to sweeten the flavor and to enhance the sleeping effects of the potion. A pinch of Bucha would help him dream of what the future would bring. Next a drop of Belladonna tincture, for she did not wish Merlin to die just yet, to prolong the sleeping effects of the potion.
This she simmered while stirring counter-clockwise for an hour before adding Agrimony to protect the foolish man from enemies that may try to find him in his enchanted sleep to hex him which would also add to the sleeping effects of the draught. A bit of cowslip would keep his body young while a bottle of Cypress increased the longevity of the potion. A bit of palm to further increase the potency with some dried periwinkle picked during the 13th night of the moon was added to enhance the potion. A few hours simmering before adding Vervain gathered at midsummer and a bit of Mandrake that she had spent the last 4 days preparing was added to enhance Merlin's dreams was added. Seven stirs to the right, seven stirs to the left, and then Nimue added Linden to deepen his sleep. As the moon reached the horizon to set, Nimue added a drop of hemlock to allow Merlin the chance to astral project before his Muggle friends who would refuse to believe their dimwitted eyes.
The potion brewed for the next 13 hours simmering down to a powder that she infused into Merlin's evening tea. She then left the foolish man to his enchanted dreams. She was not entirely certain how long he would sleep, but several decades would pass and his dream would surely be dead by the time he awoke.