Plants vs. Zombies: Battle for Neighborville

Night Cap is a character that you can play as when on the Plants side. To earn this achievement, you must earn 200 vanquishes as this character, which are kills. You can use your primary rate of fire, or any ability to make progress. You can make progress for this achievement in Giddy Park, Online, or doing Single Player missions. Although it takes longest to do it online, I would recommend it if you are planning on getting that achievement to Promote 20 characters to the rank of master. Getting 200 vanquishes will most certainly help towards getting that xp!

Good Luck!