After a long break picked up the game again and started through the class stories rather than instant boost.

 

I am at the Flashpoint:Tython Jedi temple with my character. The master Jedi kicks my butt with rocks falling from the ceiling.

 

I tried destroying the Holocron he was interfacing with and all it did was delay the inevitable. After a dozen deaths or so I left the flashpoint.

 

What am I doing wrong?

Move out of the way of the rocks. They put circles on the floor that show where they will land. When those circles are on you, *move*.

I haven't done that FP in STORY mode in a long time but from the Veteran version:

 

Yes, you want to destroy the datacrons asap so he doesn't gain as much power/health.

 

Shortly after he says "suffer" (iirc) he starts raining stuff down from the ceiling. Just keep running around and staying out of the circles, until it passes - don't overly try to attack during that time.