The inclusion of what I assume is Gorilla Grodd in the vision makes me wonder what his purpose in the narrative is? He generally is depicted as having mind control powers, so maybe she is just the figurehead and he is the threat?
Another possibility. I have been speculating that the young princess is a mind swap with the old queen (helping explain her extreme thirstiness for Flagg Sr).
Maybe Grodd facilitated the mind swap somehow?
Regardless, I agree it seems odd that her army would be enough to take down all those prominent DC heroes. I mean, they barely seemed capable of holding off Circe and some mercs of questionable quality.