While it was pretty cool and all, I can't say really like this Deus ex machina solution.
During the whole battle I couldn't really understand why the mc was just sitting back while everyone was dying when he was shown using his roots kilometers away at the previous arc. He could've wiped out most of the army on his own, or at least enough for the rest to clean up.
And the whole general thing was weird as well when he's so much stronger than him he played with him for so long...
Dunno, all of it felt like "the script demanded it to be so" which is, pretty lame