Come on the story might be good, and from comments here seems to be, but the beginning is almost indefensibly weak. He has no convincing justification to kill the Flame Emperor. If it was for revenge it would be paper thin but you might believe it. But he's going back to kill him because the Flame Emperor is "Evil" and might kill someone else? I don't buy it.
There's also no way for the Flame Emperor to find out he has the same reversion skill as him because it only triggers when one of them is killed. If MC kills FE on Day 1 then FE goes back to Day 0 and knows the MC tried to kill him. He kills the MC (who has no knowledge of Day 1) on Day 0. MC goes back to Day -1, where FE has no knowledge of Day 0 or 1. They can basically never figure out one anothers reversion skill.
That said I would be unsurprised to find out in Chapter 5 that the MC killing FE actually gives hi the reversion skill. Which would create a really weird timeline. Actually the timeline is already fucked because everytime one of them goes back in time from being killed and changes their future then they would have never gone back in time because they were never killed. Hello Paradox! Maybe the novel explains it more, alternate timelines would be the easy out.