I don't think they could have done the battle above Storms End any better. Also, kudos to Condal and co. for finally showing us it. I think it lived up to it's name.
But yeah, Vhagar is Granny dementia. She has PTSD from committing one too many war crimes in Dorne, and getting one too many a Dornish spear thrown at her from seemingly out of no where
Arrax: Breaths fire in Vhagar's face
Vhagar: *Flashbacks of personal Vietnam intensify*. "The cliffs, they're in the cliffs. The cliffs are alive!"
For those of you that don't know.
During Aegon, Visenya, and Rhaeny's invasion of Westeros, Rhaeny's was flew to Dorne to seek their subjugation. Rhaeny's found Dorne essentially empty of men and women of fighting age. But she did find the Princess Meria Martell on her seat. Meria was a very old, very blind, very obese, sickly woman. But she was the ruler of Dorne none the less.
Rhaeny's told her to submit. Meria said no, knowing full well that the Targ's would come back with their dragons. When Rhaeny's eventually said as such, Meria repeated House Martell's words and two went their separate ways.
Aegon and Rhaeny's did eventually come back and captured everything of importance. But like their initial visit, there was not a person of fighting age or caliber to be found. Meria too by this point had gone into hiding. Believing they had just conquered Dorne, Aegon left the kingdom in the hands of Lord Jon Rosby and others.
Once Aegon and his dragon's left, the Dornish hosts came seemingly out of no where. They ambushed the lords and knights who occupied their holdings, brutally torturing them until none had escaped a hellish death.
Eventually, word got back to Aegon. Aegon and Rhaeny's flew Balerion and Meraxes down to Dorne and burned everything in sight. When Rhaeny's reached the castle of Hellholt, she and Meraxes were set upon by the Dornish garrison and their Scorpions (Giant ballista's). Meraxes took a bolt to the eye and crashed upon the castle, killing Rhaenys in the process.
Aegon and Visenya spent the next few years committing innumerable atrocious in Dorne. Despite quite literally burning all of Dorne, and butchering countless civilians and soldiers, the Dornish never submitted despite losing their homes, economy, castles, food, everything.
Aegon and Visenya played tit-for-tat with the Dornish, putting bounties on various Dornish lords heads. While some were killed, most of the assassins never made it back. Countering this, the Dornish put bounties on Aegon and Visenya. On one occasion, Aegon was attacked by assassins in Kings Landing. It was only because Visenya was with Aegon at the time that he ended up living. This event led to the creation of the Kings Guard.
TLDR; Vhagar spent many years burning and butchering, while receiving many Dornish spears that seemed to come out of no where.
Dorne, despite being burnt to ash, would not be brought into the fold for another 183 years, well after the last dragon had died.