Talisman
By being a vessel for the World Spirit Sokol was able to understand many things that other people might have a hard time coming to terms with. Things that were not meant to be understood by ordinary people, like the Heavenly Tribulation.
In essence, Heavenly Tribulation was both a test and a punishment from the heavens for breaking the chains of mortality and taking the first real step into the world of cultivation.
One could only hope to 'endure' its terrible power by betting their own life against it. It was a sacred bond between man and heavenly will that must never be sullied by any other.
And the heavenly thunder that fell from the firmament was the culmination of all that a cultivator had achieved in their life and only by pushing themselves past their limits would one have a chance to survive.
Yes, "survival" was the best-case scenario and Sokol knew that better than most.