This happened last night when I was DMing. Great Wyrm casts Harm at the PC monk. Dragon fails to overcome his spell resist. I didn't have a problem with that. Then the PC started laughing at the dragon for not getting his spell through. The dragon who WAS going to spead his attacks up decided to focus on PC monk instead. He's hurt but not dead. He goes ethereal and heal himself a little. He then becomes unethereal and decides to use his abundant step to get on the dragons back who happened to be a 170' in the air. The dragon who has haste going takes thr time to fly straight up 500' and then decides to polymorph himself into a fly. The PC monk falls 670 taking away the few hitpoints he had and leaving him for dead.