Spirit Qi Furnace. The core best-selling product of the Tianyuan Realm.
In that world, where Spirit Qi was thoroughly contaminated by Demonic Qi, cultivators who left the city and safe zone only had three choices to safely supplement their Spiritual Power: Spirit Stones, elixirs, and Spirit Qi Furnaces.
But Spirit Stones were too expensive, and elixirs weren't much cheaper, only being used at critical moments.
Only the Spirit Qi Furnace was affordably priced and had many uses.
It could not only drive Magic Artifacts but also serve as a temporary supplement during combat. A high-grade Spirit Qi Furnace, aside from daily use, played a significant role during critical moments such as martial arts breakthroughs—even though the output of Spirit Qi from the furnace might harm the body, taking a little damage in exchange for a boost of Spirit Qi was a bargain at such times.