There is a blaster battle in almost every level, however the easiest one in my opinion is on "Assault on Jakku".
The best thing to remember here is to be patient. Going guns blazing will lead to you dying. Create a routine of taking cover, then quickly poking out with
and taking out a stormtrooper. Another helpful tip is to use a character's special ability when charged. This will clear out the enemies a bit faster.