Magic: The Gathering - Duels of the Planeswalkers

This achievement can be gained in Private Player matches. Just create a game and invite a friend. The friend can immediately quit out and you get credit for the win. Just repeat the process over and over. Only takes about 5-10 minutes this way.

This method will also unlock 1 card towards your deck each time. So it helps with the obtain 100% achievement as well.

Edit: It would appear that only the host can get credit towards the achievement. So just Host for your 10 wins and then switch with your friend.

If the non-host wins they still get the card towards their deck. They just don't make any progress towards the achievement.

Easy to boost, but either way, you just need to win 10 matches on Xbox live.

If you're going to boost with a friend, you can actually just re-start the matches without leaving the lobby afterwards, you can just "re-ready" yourselves and the match would start again.

Should take about an hour, depending on how fast you get decent cards in your hand.