Normally, in the process of Foundation Establishment, there is no need to go through such a huge deal, even for an Immortal Grade cultivation. It's just that at the moment of successful Foundation Establishment, a powerful aura will burst forth.
But if you choose a location in advance, it generally won't attract much attention.
As for the Heavenly Tribulation, if watched from a distance, most people would mistake it for a thunderstorm and not pay too much attention. Every day, many people in the Spirit Realm undergo the Tribulation, so unless there is a deep-seated grudge, very few people pay attention to it.
But when it comes to Heavenly Grade Foundation Establishment, it is entirely different.
