achievment all alone

i want to do it.Is the last one that i need to complete all the achievments of halo reach. can you help me?

> i want to do it.Is the last one that i need to complete all the achievments of halo reach. can you help me?

The way I did it, was go to the Infection Playlist, and play until Uplink or the other Defiant Map comes up, that’s the only way I know how to do it.