So I finally got lucky and unlocked the crystal cruiser, the Bravais. I'd like to do 2 of the achievements for it so that I can unlock its alternate layout. Getting the No Escape achievement was relatively easy (suicidal, but easy) so now I just need 1 more; Crystal Vengeance seems very tricky to get deliberately, so I figured I'd go for the Clash of the Titans achievement.
It says you need to destroy 15 Rock ships (including pirate Rock ships) with the crystal cruiser. Can I do that over multiple runs, or do I have to kill 15 in a single run?