all she needs to do is become intangible then she can do whatever she wants to him. bricks don't do well against sersi. at all. i guess you could argue a blitz may work a couple out of 10, but i'd say she could weather it most of the time long enough to phase or teleport so i doubt it would even matter much even if he did blitz. and it's not like he ever blitzes with his overrated "planet busting powa!!1!" anyway.
she has a million ways to f him up for a vast majority.