This is like the Fairy Tail climax against Acnologia but with less friendship and more cleaning, what with the battle being on physical and spiritual levels at the same time.
But I'll take this "climax battle against just 1 really strong boss where everyone contributes" over "2 massive armies so the useless heroes can defeat the useless villains" any day. Looking at you, Endgame. I legit think the climax battle in Endgame is bad, so stone me.
I'm glad the last 3 dragons got to appear instead of just staying dead after kicking the bucket, but yeah, like everyone before me I do wish we had chapters dedicated to them.
Ending in 4 volumes is not bad, I guess. Certainly fared better than the author's previous work which ended in 2.