Dominate is a multiplayer game mode. While the achievement description states "map" it is really referring to "game" as there is only one map available. You can easily boost this by having an opponent quit after you capture one zone and register a score, which takes about 20 seconds.
Note that this achievement can only be unlocked in a ranked match.
When you start the game, move toward your minion spawn point directly in front of you, hold down to select it and press so that you have one minion. Go down the hill in front of you and up to the glowing doorway (it is indicated on your minimap with a skull). You you get a notification on the bottom of the screen that you can capture the zone, press so your minion will capture it. You will score 25 points five seconds later, at which point your opponent can quit and you will win the game.