I was thinking about some epic event where no matter where you are, you get a message from your ghost something like this: "Guardian, I've received an urgent distress signal from the Speaker. Aparently a ship full of refugees has crashed and is in danger of being overrun. They desperately need your help." If you are at the tower, these six man drop ships arrive for you and your buddy to jump on. You might end up with some random dudes, but lets say 20 people are in the tower...18 respond, three six man drop ships arrive...everyone gets to go and each drop ship spawns a similar but seperate rescue mission...one group could end up on the moon, the other on Mars, etc...you dont have to go, but if you do, you have a grater chance at good loot. The missions would be hoard missions with wave of increasingly difficult enemies with a good, hard boss fight to end it...once the baddies are clwared out, a transpot ship can come in and ferry survivors.