I did Stone Vigil with a PuG, crashed in flames at first boss. I was the healer.

I've had zero problems healing any other dungeon.

This dungeon, the first boss (Chun-Yun or something) does a flame attack that hits the tank for 80-90% hp and then kills him with an autoattack before I can even get a Physicks heal off. DPS blackmage called me "fucking noob healer!" and quit.

Did I have bad luck and got a tank made of paper tissue, or is that flame breath attack he does intended to hit for 80% of a tank's health? Because the damage was plain unhealable unless I was turreting heal even if the tank was full and by some luck one of the heals landed as soon as he took damage. Can't react at all to that kind of damage.