Huge knight(GOT)

I am the big fan of GoT tv series, i think as most of us) so i decided imagine the huge knight who could be fighting for Cersei, and as you could see would be in 3-4 times even bigger than her current guard Gregor Clegane (aka The Mountain). I hope Cersei's faithful lackey Qyburn introduce him as the newest member of the King's Guard in a next season. Other wise how the Lannisters going to fight with a White walkers army and Dragon queen allies at the same time)