The essence of the divine blood potion was made using Kalunu's blood. There was no other way. The curse on the Tree Spirits originated from the bloodline and also the gods in the past. After a long time, it was impossible to trace back to the past, and no one knew which god cast the curse. Even that god himself might have already fallen.
However, even so, the power rooted in the bloodline was particularly powerful and could not be eradicated under ordinary circumstances. After all, a god was a god. The only way to eliminate it was to use a power of the same level.
Therefore, before this, despite using all kinds of methods, Kalunu realized that it was still ineffective. Ultimately, he had no choice but to use his divine power to slowly cleanse the curse in their bodies, changing their fundamentals.
