Battlefield 3
34 Achievements
EA Play
Dominator
Won a round in Conquest Domination
How to unlock the Dominator achievement in Battlefield 3 - Definitive Guide
This achievement is really simple. All you have to do is play through a game of Conquest Domination and win, really easy. This is a pretty fun game mode. If your having trouble getting this achievement, you could always search for a server that does not have a lot of players on it. I found Operation 925 the easiest to play on. Hopefully, the admins aren't kick happy, and you will have an easier time winning the game. Good Luck!
This should come naturally as you will win a round at some point during your playtime. Just make sure you're playing 'Conquest Domination' and not just 'Conquest' or 'Conquest Assault'.