Hope for rules changes or points drops? 

This is a tough matchup, marines aren't in a great spot, and within marines white scars don't really stand out. Where the obsekh dynasty necrons are strong with their easy to score secondaries. 

I would suggest picking up a set of the tempest of war cards - each turn you draw your secondaries so not able to just hammer easy ones, have to adapt your plan based on what cards you draw.

I play primaris only marines (currently white scars) vs my friends obsekh necrons. They kick my ass every time. I can't seem to bring enough firepower to blow them off the objective markers before they rack up enough vp that I can't catch up.

We're both playing 1000 pt Patrol forces.

Any advice?

Primaris vs Necrons help plz