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Then, I created the dagger. I tethered her spirit to it so I could control and prevent her reign of terror.
Merlin to Emma Swan src

The Tethering Potion is a magic potion featured on ABC's Once Upon a Time. It first appears in the seventh episode of the fifth season.

In some cases, a Tethering Spell can be used instead of a potion.


Before First Curse

After Nimue shatters Excalibur to prevent removal of her Dark One powers, the sorcerer Merlin creates a tethering potion to bind Nimue to Excalibur's broken half, the Dark One's dagger. With this, he succeeds in forcing Nimue to obey the commands of whoever possesses the dagger. At some point, Merlin records information on the tethering potion in one of his books, which he keeps in his tower. ("Nimue")

Before Third Curse

While plotting her escape from Regina, Zelena helps King Arthur get one of Merlin's spell books and tethering Merlin to Excalibur. Arthur then assumes control of Excalibur and commands Merlin to do his bidding, which ends later when Hook makes him forfeit Excalibur. ("Nimue", "Birth")

Before Hook succumbs to a fatal wound from Excalibur's blade, Emma tries to save him by tethering his life to Excalibur. In doing so, she releases Merlin from the tether that Arthur put on him, but this results in Hook being revived as a new Dark One. ("Nimue")

After Third Curse

Realizing he has a chance to take back the Dark One's powers, Mr. Gold uses a tethering potion on Excalibur, before giving the sword to Emma. While Emma wishes to sacrifice herself to prevent the Dark Ones from taking people's souls to the Underworld, Hook ultimately gives up his life to protect the townspeople. With Hook's death, all the darkness that once sustained the Dark Ones' magic should disappear into nothingness, however, because of the tethering potion, the powers of all previous Dark Ones return into Mr. Gold. ("Swan Song")

After Third Curse

Unable to convince Maurice to give true love's kiss to Belle and wake her from the sleeping curse, Mr. Gold takes drastic measures to gain enough magic to reawaken his wife by binding Storybrooke's magic to a piece of the Olympian Crystal. He then departs for New York City and checks into a hotel room, where he prepares a summoning circle with intentions of using the crystal to wake up Belle. This plan is halted when Mr. Hyde, from the Land of Untold Stories, steals the box containing Belle, in order to have leverage against Mr. Gold. ("Last Rites", "Only You")


Props Notes

  • Merlin's recipe for a tethering spell reads:[1]
I cause these changes to take place in
conformity with my will

So must it be!

The first requisite for being the
arbiter of physical transformation is
thorough qualitative and
quantitative understanding of the
consternation of the blade, the
first party.

This must be repeated in
honor of the second, sentient party.
Once this has been achieved these
subtle energies may be entwined.

To bind two disparate phenomena.
To make them one in an act of
diabolic synergy.
Speaketh the following incantation:

'He who will wield
this dread blade
Shall be fast held to it its purpose.
The kind who cleft thee so
in twain I held in thrall,
their name be graven.'