Two for One

Two for One is a Halo 3 multiplayer achievement. It was awarded for killing two enemies with one Spartan Laser shot in a ranked free for all playlist (i.e. Lone Wolves). The achievement awarded the player 5 Gamerscore.

It is represented by a white circle with a red star. On top, two skulls and a Spartan Laser silhouette.

Following the shutdown of Xbox 360 Halo online services on January 13, 2022, this achievement is no longer attainable.

Method 1
One way to get this achievement was to use the Spartan Laser on King of the Hill gametypes, where everyone would be grouped inside the hill and not able to pay attention to a laser charging up in the background.

Method 2
Another way was to have the Spartan Laser on maps that contain s, and all the player would need to do is charge the laser and wait for someone to board the Ghost. Using the Laser to destroy the Ghost would result in the driver and the boarder being "Lasered".

Method 3
Some players were able to find other players who would help them boost the achievement.

Method 4
In the Double EXP Weekend playlist Legendary Brawl, occasionally there would be two players on a Warthog, which granted players an opportunity to earn the achievement.

This method would only work on Avalanche, Standoff and Rat's Nest, as Ghost Town did not have a Warthog (but it has several Mongooses) and the Sandtrap variant in the playlist was "FFA Modified" and did not qualify.

Trivia

 * It was not necessary for the laser itself to travel through both of enemies, just that the single shot killed two people.
 * Due to the difficulty of getting this achievement, many players refer it as one of the most difficult achievements to obtain among the original 40 achievements.