Huo Yuhao had asked Orochimaru for a chakra cultivation method and a Wood Release potion because he intended to cultivate a third power system.
The chakra system!
The cultivation method was the training manual, while the Wood Release potion was the key to getting started.
As everyone knew, the world of Naruto was really a world where bloodlines decided everything. Without the bloodline of the Sage of Six Paths, or of people such as those in the Ninja Sect to whom the Sage had passed his chakra, one could not cultivate chakra.
That was because their bodies had no chakra seed. Huo Yuhao also needed a key to extract chakra, and that key was a potion made from Hashirama Senju's Wood Release.
Orochimaru could produce Wood Release potions, but his products were unlicensed, uncertified, and unregulated, with an extremely high failure rate. To date, the only person who had awakened Wood Release after using one was Yamato, the landscaping ninja.
But Huo Yuhao had no fear. His genes were incomparably powerful, and he had cultivated every cell in his body to the peak of Advanced War God. Even if the fusion failed, his life would not be in danger.
Once he possessed a bloodline from Naruto, he could begin cultivating chakra, then use the Impure World Reincarnation Technique to summon his mother's soul back.
The Impure World Reincarnation Technique was a forbidden spell in Naruto, an evil art that sacrificed living people to drag the souls of the dead out of the Pure Land and into reality to fight for the caster.
The Pure Land in the world of Naruto was that world's Netherworld. But that did not really matter; even souls that were not in the Pure Land could still be summoned.
For example, when Orochimaru reincarnated Konoha's Four