Mostly, you just need to not get unlucky. FFG's rather short sighted scoring system does not award partial points for even a one hull decimator, so a bad toss or two means your loss no matter what you do.

As for the phantom, HLCs (w/ re-rolls) are your friends

Kill the phantom first and you've broken the list's back. Decimators can do some damage but they can't take it in return for long.