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Party missions
From The re-PSUPedia
Party missions are unique missions that require at least two players to initiate and complete. As with story missions, there are a few special conditions that party missions follow. First, a party must be formed before the mission can begin, however no NPCs may be in the group. Second, Scape Dolls cannot be used; incapacitation leads to immediate failure. Likewise, if a player leaves the party for any reason or if the leader is changed, the mission will end.
