Another of my "Does This Exist/How Common Is This" Threads. This time I'm looking for a Cultivation story where the MC reaches Immortal Realm simply by building up their "Foundation" to the point where it raises them up. Please note, I am NOT talking about following one cultivation technique from foundation to immortality, nor am I talking about having a "strong foundation" at every level before reaching the next level. I'm talking about reaching the Immortal Level of cultivation using only a technique intended for building the foundation level. There are multiple ways in which a story could do this that I can think of. They could, for example, build up a foundation so strong that their cultivation automatically starts building up the next stage of cultivation (either giving them a tribulation as a side effect, or when they reached the absolute limits of how strong a foundation can be). Alternatively, they could build up a foundation strong enough that the Heavens consider them equal in power to Immortals, and either makes them Immortal, or gives them rapid Tribulations until they are forced into the Immortal Realms. Or the MC's foundation could grow so strong that it starts processing the "higher" forms of energy that normally come after improving one's rank automatically (and probably triggering tribulation), despite the individual not really advancing their cultivation method beyond the Foundation Level. Please note, I know of and accept that "I have refined Qi for 3000 Years" does fit this request, though it isn't really what I want to find. I'm looking for someone who, either through ignorance or stubbornness, purposefully follows a Foundation Level cultivation technique to at least Immortal Level. I have refined Qi for 3000 Years has the MC forcefully trapped in the Qi Formation Stage, unable to find a way to progress beyond it, and not for lack of trying or experimenting. While if what I want does exist, it will likely also be a comedy cultivation novel, the difference between "Obnoxious OP MC is OP, but has a low realm" and "Ignorant MC is OP despite his low realm" is significant.
I'd say "The World After the Fall" somewhat fits the bill. MC raises his skill one a single skill, thrust, so much that he basically becomes OP.
Dao of Evil in watpatt MC didn't use an Immortal cultivation, he is Qi Condensation cultivator who never upgrade his power to Foundation Stage, Core Realm, Nascent Soul, etc But he did gain power equivalent to those realm by built and amassed hundred of Qi Condensations.