Escalation works a lot better if you have 3 other players with you. As each of the 4 characters you choose from have very useful abilities that help out everyone. (YOU CAN NOT HAVE MORE THAN ONE OF THE SAME CHARACTER IN A ROUND. EVERYONE WILL BE A UNIQUE CHARACTER). You will have to complete all 15 waves for all the maps: Ancients,Oblivion, DownFall, Ignition. You can choose to play in a private match, and set the difficulty to easy. Or you can play a public match, also choosing easy, with other people. This game mode also works better if everyone works as a team and doesn't go around getting killed. The better the communication the more successful you and your team will be. Also you have three lives. So if you fail a wave or die during a wave, you will loose a life. Unfortunately there is no way to choose what map you want to play. So it is recommended to do all 4 maps in one go.
NOTE: You will still get the achievement even if you join mid-way through a wave. So you might get lucky and be put into a game that is already on 14 or 15.
Click HERE to find partners to play with online or to create boosting sessions.