Having millions fighting is absurd. I'm not even sure that the translator has been right about the numbers since they don't add up at times. Even so, the writer did a poor job visualizing the destruction. It would have been better if they showed massive groups of troops clashing or had a massive kill feed listing xp each time his minions let off a huge attack. I also wish it didn't go so easily for them. I would have liked to see them succumb to a particular tactic or a group of a type of monster that was harder to handle. At times this manga has a grittier feel and I would have loved to see some real carnage, mountains of corpses, things like that.