Have you played the game Qistina? That usually happens when the dragon is quite a few levels above the party and the party is usually under geared. The game gives you ample chance to run away and reattempt it. I also remember the High dragon at Haven and flemeth one shot some of my squishies when I first tried to fight it years ago with the grab attack so this ain't anything new really. The encounters at equal level or even a few levels above seem quite fair.