"I have to admit, brother Haitin," Aksai said after a moment, "this Spirit tea is remarkable."
Haitin smiled. "It's just a common resource that my sect produces in a controlled greenhouse. But I'm glad you think so.
It's one of our sect's lesser-known treasures, but those who use it regularly see real improvements in their cultivation.
Of course, it's not something we hand out to just anyone. We usually save it for our talented newbies– cultivators in the Spirit Refining realm who show immense talent. We use this tea to hasten their cultivation journeys to some extent while also enabling them to unearth their potential.
When the Spirit Refiners use this tea during the late-stages of the 1st realm, they develop a certain tolerance towards it by the time they are ready to break into the Foundation Building realm. Once they break into the 2nd realm, the tea becomes ineffective for them no matter how much of it they consume."