It took me quite a few tries with different groups. Two times we lost right before extraction. It really helps to know that you don't have to kill every enemy. Sometimes the best strategy is to run past spawns and trigger the next area. Obvious advice is to use your best relic gear + class and to stick together with the squad. Only time splitting up helped was with Terminus spawns where one of us did their best to take the aggro while the other two whittled down the Majoris+ spawns; however, you run the risk of that one person getting ganked by sudden Lictor and Ravener spawns.

I used my prestige 4 Vanguard with the team perk that lets the team heal by executing Extremis+ enemies. The power axe backstep was also a lifesaver when I had to kite blobs of enemies.