Remember when he started from the bottom then worked his way up to build a whole fortress for his family and forming alliance with strong figures?
Yea scratch all that, because in the end none of that meant anything since here he is fighting an enemy who's supposedly got monstrous strength that can single-handedly wipe out or take on all legendary experts currently known to us. Apparently the heavenly realms is an arbitrary scale too as everyone and their mother are all "experts" but get blasted by the Emperor anyway.
The author is pulling the bullshit cliche by letting Xinghe attain some stupidly overpowered technique that can somehow turn the tide of the battle instantly (I'm speculating but still). All just from touching an ancient stone and basically saying I agree to the terms and conditions.
I liked reading this because of how MC started as a puny martial artist and actually climbed his way up but it seems like the author got overly-ambitious with the lore, character development and relationships and ultimately got tired of trying to think up new logical decisions Xinghe can possibly make to keep the story solid. Seems to be the case with most works where the MC is the underdog who appears logical and calculating at first but then later the author(s) is like nah fam I've raked up enough of a reading fanbase so I'm outtie let's cut the crap and let the MC win no matter what.
But hey, reading from the comments it seems we're near the ending so that's good.