But, but… they needed the Lannister army…
Strictly speaking, not even the Unsullied in their high numbers would have had a chance against the Golden Company, so I don’t even know how and why they are going to siege or invade King’s Landing. King’s Landing, thanks to Qyburn, Qyburn who also negotiated the Iron Bank deal, had Ballistas installed on King’s Landings outer wall, perhaps also on the inner wall to also act as anti-air.
Just to add, the Golden Company in the books are 10 000 strong, in the series they made them 20 000 strong.
Cercei have to be assassinated. Arya or brother Jaime, the kill is in their hands. And still, then there is Emporer Qyburn and Darth Mountian who would probably make better rulers than any other person in Westeros, but one will probably go out quickly and the other is lined up with the Super, a-hem, Cleganebowl. Fan service.
This battle is going to be cheaper than the Night King invasion.
Euron also doesn’t give a toss whether a dragon dive attacks his ship, it is to be expected, a dragon is an aerial unit, duh. Just have more ships, he has ~1000, positioned more to the back to guard those angles. It is not rocket science, other than a ballista not really able to shoot up into the air, due to poor velocity, it is more a lob at the point it is too heavy at the high arc. Fiction, leaving it at that, but scorpions would have made more sense.
The showrunners did poor research, and they didn’t have any reason to cheapen anything. Better writing was required.