As soon as he came back from the palace Wu Long helped Yu Huan create pills from the Violet Retribution Hydrangeas, which purpose was to strengthen the Yin Qi and Yin Root of his ladies. Though he only lent her some of his Soul Power and Spiritual Qi, as they have discussed the methods she would use and the recipe for quite some time before.
Most recipes including this ingredient for Mortal Grade pills actually deliberately lowered its potency, as this flower's power was simply too tyrannical for use in Nine Mortal Realms.
However, Wu Long did the complete opposite, enhancing the effects of the medicine with the methods from recipes of Profound Grade pills, though not completely reaching that level yet as it required Profound Qi to refine those pills.