What does the "Fire Multiple" setting for a Ship Spawner even do? I haven't noticed any changes when changing that.
It changes the ship's fire rate. 0 makes the ships fire equally fast as the player's, 1 is about twice as fast, 2 is probably about 3x as fast, etc. In a certain story mission there are ship spawners with a fire multiple of 8 or so and they're pretty brutal.
https://www.youtube.com/watch?v=olfXXqZGf0o&feature=youtu.be