Yoki Synchronization

Definition
Yoki Synchronization is essentially the precursor to any sort of Yoki Manipulation. To perform this technique, the user analyzes his or her target's yoki, may it be that of a Yoma, Claymore, or Awakened Being, and then aligns the wavelength of his or her yoki with the target's wavelength. This, in effect, causes the two yoki auras to synchronize and become connected, allowing the user to manipulate the opponent's aura - and their bodies in turn - in however manner they so wish, such as either increasing or decreasing yoki flow or redirecting attacks.

Known Yoki Synchronizers
The first character to use this technique was God-Eye Galatea, who utilized it during the "The Witch's Maw" and "The Deep Abyss of Purgatory" arcs to control Dauf's attacks and prevent Clare from surpassing her limit while trying to land a blow on Riful of the West. After observing what Galatea had done, Clare attempted to emulate her and synchronized with an Awakened Jean during the same arc, barely managing to pull the Number 9 back to human form by supressing her Awakening. In the Invasion of Pieta, a fatally wounded Jean would go on to repay Clare's help in full, using the same technique when she was about to Awaken following the defeat of Rigaldo.

The next in line to exhibit the skill was Cynthia, who used it both for standard Yoki Manipulation and for healing purposes after the seven-year timeskip. Eventually, she taught Yuma how to perform the skill in order to aid her with healing other warriors.

Thirdly came Renee, who was forced by Riful and Dauf to use this technique to try and Awaken the merged Rafaela and Luciela, though this attempt, for all intents and purposes, ended in failure. However, Clare picked up where she left off later on, unconsciously synching with the Rafaela-Luciela being and becoming drawn into the remains of Rafaela's consciousness. In the encounter that followed, Rafaela used the skill on Clare in order to be able to manipulate the younger warrior's mind, placing the entirety of her memories within Clare so that she would "discover that which [she] should know."

Finally, Roxanne of Love and Hate is the latest user of this ability, being gifted with it since her time as Number 35. Synchronizing her yoki with a target was part of a Yoki Manipulation technique she used during her warrior days to completely erase her presence, hiding her from both physical senses and yoki sensing techniques. This was how she was able to view and copy the techniques of other warriors (No. 31 Uranus's "Blade of Evil," No. 9 Neideen's Yoki Sensing technique, and No. 5 Elizabeth's "Beautiful Sword") for her own use.